Method and apparatus for transmission and reception of sidelink feedback in wireless communication system

ABSTRACT

The present disclosure relates to a communication method and system for converging a 5th-Generation (5G) communication system with a technology for Internet of Things (IoT). Methods and apparatuses are provided in which first sidelink data and second sidelink data are received from one or more terminals. It is determined whether a first resource for transmitting first feedback information for the first sidelink data and a second resource for transmitting second feedback information for the second sidelink data overlap each other. When the first resource and the second resource overlap each other, feedback information corresponding to one of the first feedback information and the second feedback information having a higher priority, is transmitted to the one or more terminals. A priority of each of the first feedback information and the second feedback information is based on sidelink control information scheduling each of the first sidelink data and the second sidelink data.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is based on and claims priority under 35 U.S.C. §119(a) to Korean Patent Application Nos. 10-2019-0051796 and10-2019-0058405 filed on May 2, 2019 and May 17, 2019, respectively, inthe Korean Intellectual Property Office, the disclosures of which areincorporated herein by reference in their entireties.

BACKGROUND 1. Field

The disclosure relates generally to a method and an apparatus fortransmitting feedback on a data transmission in a sidelink, and moreparticularly, to a method for configuring a hybrid automatic repeatrequest-acknowledgment (HARQ-ACK) codebook and a method for determininga timing of transmitting a feedback when data is transmitted to asidelink and HARQ-ACK information about the corresponding data istransmitted from a receiving terminal to a terminal having transmittedthe data.

2. Description of Related Art

To meet the demand for wireless data traffic having increased sincedeployment of 4G communication systems, efforts have been made todevelop an improved 5G or pre-5G communication system. The 5G or pre-5Gcommunication system is also referred to as a ‘Beyond 4G Network’ or a‘Post LTE System’. The 5G communication system is implemented in higherfrequency (mmWave) bands (e.g., 60 GHz bands), so as to accomplishhigher data rates. To decrease propagation loss of the radio waves andincrease the transmission distance, beamforming, massive multiple-inputmultiple-output (MIMO), full dimensional MIMO (FD-MIMO), array antenna,analog beam forming, and large scale antenna techniques are discussed in5G communication systems. In addition, in 5G communication systems,development for system network improvement is under way based onadvanced small cells, cloud radio access networks (RANs), ultra-densenetworks, device-to-device (D2D) communication, wireless backhaul,moving network, cooperative communication, coordinated multi-points(CoMP), reception-end interference cancellation and the like. In the 5Gsystem, hybrid FSK and QAM modulation (FQAM) and sliding windowsuperposition coding (SWSC) have been developed as an advanced codingmodulation (ACM), and filter bank multi carrier (FBMC), non-orthogonalmultiple access (NOMA), and sparse code multiple access (SCMA) have beendeveloped as an advanced access technology.

The Internet is now evolving to the Internet of things (IoT) wheredistributed entities exchange and process information without humanintervention. The Internet of everything (IoE), which is a combinationof the IoT technology and the big data processing technology throughconnection with a cloud server, has emerged. As technology elements,such as “sensing technology”, “wired/wireless communication and networkinfrastructure”, “service interface technology”, and “securitytechnology” have been demanded for IoT implementation, a sensor network,a machine-to-machine (M2M) communication, machine type communication(MTC), and so forth have been researched. Such an IoT environment mayprovide intelligent Internet technology services that create a new valueto human life by collecting and analyzing data generated among connectedthings. IoT may be applied to a variety of fields including smart home,smart building, smart city, smart car or connected cars, smart grid,health care, smart appliances and advanced medical services throughconvergence and combination between existing information technology (IT)and various industrial applications.

Various attempts have been made to apply 5G communication systems to IoTnetworks. For example, technologies such as a sensor network, MTC, andM2M communication may be implemented by beamforming, MIMO, and arrayantennas. Application of a cloud RAN as the above-described big dataprocessing technology may also be considered to be as an example ofconvergence between the 5G technology and the IoT technology.

In a wireless communication system, and particularly, in a New Radio(NR) system, as data is transmitted from a transmitting end to areceiving end, the receiving end transmits HARQ-ACK feedback informationof the corresponding data to the transmitting end after receiving thedata. For example, in transmitting downlink data, a terminal transmits,to a base station, HARQ-ACK feedback information of the data transmittedfrom the base station on a configured resource. Also, in transmittingsidelink data, a receiving terminal may transmit an HARQ-ACK feedback toa transmitting terminal. Such HARQ-ACK feedback may be used asinformation for the transmitting terminal to determine retransmission orthe like. A physical sidelink feedback channel (PSFCH) may be used as aphysical channel on which the receiving terminal transmits the HARQ-ACKfeedback.

Because all slots of the sidelink may not have resources on which thePSFCH can be transmitted, it may be necessary for the receiving terminalto transmit a plurality of pieces of HARQ-ACK feedback information on aplurality of pieces of data on one PSFCH.

SUMMARY

According to an embodiment, a method is provided that performed by aterminal in a communication system. First sidelink data and secondsidelink data are received from one or more terminals. It is determinedwhether a first resource for transmitting first feedback information forthe first sidelink data and a second resource for transmitting secondfeedback information for the second sidelink data overlap each other.When the first resource and the second resource overlap each other,feedback information corresponding to one of the first feedbackinformation and the second feedback information having a higherpriority, is transmitted to the one or more terminals. A priority ofeach of the first feedback information and the second feedbackinformation is based on sidelink control information scheduling each ofthe first sidelink data and the second sidelink data.

According to an embodiment, a terminal in a communication system isprovided. The terminal includes a transceiver and a controller. Thecontroller is configured to receive, from one or more terminals via thetransceiver, first sidelink data and second sidelink data. Thecontroller is also configured to determine whether a first resource fortransmitting first feedback information for the first sidelink data anda second resource for transmitting second feedback information for thesecond sidelink data overlap each other. When the first resource and thesecond resource overlap each other, the controller is further configuredto transmit, to the one or more terminals via the transceiver, feedbackinformation corresponding to one of the first feedback information andthe second feedback information having a higher priority. A priority ofeach of the first feedback information and the second feedbackinformation is based on sidelink control information scheduling each ofthe first sidelink data and the second sidelink data.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other aspects, features, and advantages of the disclosurewill be more apparent from the following detailed description, whentaken in conjunction with the accompanying drawings, in which:

FIG. 1 is a diagram illustrating the basic structure of a time-frequencydomain that is a radio resource region in which data or a controlchannel is transmitted on a downlink or an uplink in an NR system;

FIG. 2 is a diagram illustrating frequency and time resources allocatedfor information transmission in an NR system, according to anembodiment;

FIG. 3 is a diagram illustrating frequency and time resources allocatedfor information transmission in an NR system, according to anotherembodiment;

FIG. 4 is a diagram illustrating a process in which one transport blockis divided into several code blocks and cyclic redundancy check (CRC) isadded to each of the code blocks, according to an embodiment;

FIG. 5A is a diagram illustrating one-to-one communication, that is,unicast communication, performed between two terminals through asidelink, according to an embodiment;

FIG. 5B is a diagram illustrating a groupcast communication in which oneterminal transmits common data to a plurality of terminals through asidelink, according to an embodiment;

FIG. 6 is a diagram illustrating a process in which terminals havingreceived common data through groupcasting transmit information relatedto data reception success or failure to a terminal having transmittedthe data, according to an embodiment;

FIG. 7 is a diagram illustrating a state in which a synchronizationsignal of an NR system and a physical broadcast channel are mapped ontoeach other in a frequency and time domain, according to an embodiment;

FIG. 8 is a diagram illustrating what symbols one synchronizationsignal/physical broadcast channel (SS/PBCH) block is mapped onto in aslot, according to an embodiment;

FIG. 9 is a diagram illustrating symbols on which SS/PBCH blocks can betransmitted in accordance with a subcarrier spacing, according to anembodiment;

FIG. 10 is another diagram illustrating symbols on which SS/PBCH blockscan be transmitted in accordance with a subcarrier spacing, according toan embodiment;

FIG. 11 is a diagram illustrating a resource pool that is defined as aset of resources on time and frequency being used for sidelinktransmission and reception, according to an embodiment;

FIG. 12 is a diagram illustrating a scheduled resource allocation (mode1) method in a sidelink, according to an embodiment;

FIG. 13 is a diagram illustrating a UE autonomous resource allocation(mode 2) method in a sidelink, according to an embodiment;

FIG. 14A is a diagram illustrating a method for configuring sensingwindow A for UE autonomous resource allocation (mode 2) of a sidelink,according to an embodiment;

FIG. 14B is a diagram illustrating a method for configuring sensingwindow B for UE autonomous resource allocation (mode 2) of a sidelink,according to an embodiment;

FIG. 14C is a diagram illustrating a method for configuring sensingwindow A and sensing window B for UE autonomous resource allocation(mode 2) of a sidelink, according to an embodiment;

FIG. 15 is a diagram illustrating a mode 1 method for performingsidelink data transmission through reception of scheduling informationfrom a base station, according to an embodiment;

FIG. 16 is a diagram illustrating a mapping structure of physicalchannels mapped onto one slot on a sidelink, according to an embodiment;

FIG. 17 is a diagram illustrating a resource capable of transmitting andreceiving a PSFCH for each slot is configured, according to anembodiment;

FIG. 18 is a diagram illustrating a resource capable of transmitting andreceiving a PSFCH every four slots is configured, according to anembodiment;

FIG. 19 is a diagram illustrating a terminal determining a slot fortransmitting an HARQ-ACK feedback, according to an embodiment;

FIG. 20 is a diagram illustrating the maximum number of HARQ-ACKfeedback bits that a terminal should transmit on one PSFCH, according toan embodiment;

FIG. 21 is a diagram illustrating a terminal determining a slot fortransmitting an HARQ-ACK feedback, according to another embodiment;

FIG. 22 is a diagram illustrating a terminal determining a slot fortransmitting an HARQ-ACK feedback, according to another embodiment;

FIG. 23 is a diagram illustrating a terminal determining a slot fortransmitting an HARQ-ACK feedback, according to another embodiment;

FIG. 24 is a diagram illustrating a terminal determining a slot fortransmitting an HARQ-ACK feedback, according to another embodiment;

FIG. 25 is a diagram illustrating physical slot indexes and logical slotindexes of slots included in a resource pool configured in accordancewith resource pool configuration in physical slots, according to anembodiment;

FIG. 26 is a diagram illustrating a time when terminal 1 and terminal 2should transmit PSFCHs in the same slot for HARQ-ACK feedbacktransmission for respective transmitted PSSCHs when terminal 1 andterminal 2 perform signal transmission and reception by a connectionthrough unicast or groupcast communication in a sidelink, according toan embodiment;

FIG. 27 is a diagram illustrating a time when UE 1 should transmit twoPSFCHs in the same slot for HARQ-ACK feedback transmission forrespective transmitted PSSCHs when terminal 1 performs signaltransmission and reception with terminal 2 and terminal 3 by aconnection through unicast or groupcast communication, according to anembodiment;

FIG. 28 is a block diagram illustrating the internal structure of aterminal, according to an embodiment; and

FIG. 29 is a block diagram illustrating the internal structure of a basestation, according to an embodiment.

DETAILED DESCRIPTION

In an NR access technology, various services have been designed so thatthey can be freely multiplexed on time and frequency resources.Accordingly, waveform/numerology and reference signals can bedynamically or freely allocated as needed for the correspondingservices. In order to provide optimum services to a terminal in wirelesscommunications, it is important to optimize the data transmissionthrough measurement of the channel quality and the interference amount.Thus, it is essential to measure an accurate channel state. However, incase of the 5G channel, in contrast with the 4G communication in whichthe channel and interference characteristics are not greatly changeddepending on the frequency resources, the channel and interferencecharacteristics are greatly changed depending on the services. Thus, itis necessary to support a subset of frequency resource group (FRG)dimensions that make it possible to dividedly measure the channel andinterference characteristics. In the NR system, supported services maybe divided into categories of an enhanced mobile broadband (eMBB),massive machine type communications (mMTC), and ultra-reliable andlow-latency communications (URLLC). The eMBB may be a service aimed athigh-speed transmission of high-capacity data, the mMTC may be a serviceaimed at minimization of a terminal power and accesses of a plurality ofterminals, and the URLLC may be a service aimed at high reliability andlow latency. Different requirements may be applied in accordance withthe kinds of services applied to the terminal.

Hereinafter, embodiments of the disclosure will be described in detailwith reference to the accompanying drawings.

In describing the embodiments, explanation of technical contents thatare well known in the art to which the disclosure pertains and are notdirectly related to the disclosure will be omitted. This is to describethe subject matter of the disclosure more clearly without obscuring thesame through omission of unnecessary explanations.

For the same reason, in the accompanying drawings, sizes and relativesizes of some constituent elements may be exaggerated, omitted, orbriefly illustrated. Further, sizes of the respective constituentelements do not completely reflect the actual sizes thereof. In thedrawings, the same drawing reference numerals are used for the same orcorresponding elements across various figures.

The aspects and features of the disclosure and methods for achieving theaspects and features will be apparent by referring to the embodiments tobe described in detail with reference to the accompanying drawings.However, the disclosure is not limited to the embodiments disclosedhereinafter, and it can be implemented in diverse forms. The mattersdefined in the description, such as the detailed construction andelements, are only specific details provided to assist those of ordinaryskill in the art in a comprehensive understanding of the disclosure, andthe disclosure is only defined within the scope of the appended claims.In the entire description of the disclosure, the same drawing referencenumerals are used for the same elements across various figures.

In this case, it will be understood that each block of the flowchartillustrations, and combinations of blocks in the flowchartillustrations, can be implemented by computer program instructions.These computer program instructions can be provided to a processor of ageneral purpose computer, special purpose computer, or otherprogrammable data processing apparatus to produce a machine, such thatthe instructions, which execute via the processor of the computer orother programmable data processing apparatus, create means forimplementing the functions specified in the flowchart block or blocks.These computer program instructions may also be stored in a computerusable or computer-readable memory that can direct a computer or otherprogrammable data processing apparatus to function in a particularmanner, such that the instructions stored in the computer usable orcomputer-readable memory produce an article of manufacture includinginstruction means that implement the function specified in the flowchartblock or blocks. The computer program instructions may also be loadedonto a computer or other programmable data processing apparatus to causea series of operational steps to be performed on the computer or otherprogrammable apparatus to produce a computer implemented process suchthat the instructions that execute on the computer or other programmableapparatus provide steps for implementing the functions specified in theflowchart block or blocks.

Also, each block of the flowchart illustrations may represent a module,segment, or portion of code, which includes one or more executableinstructions for implementing the specified logical function(s). Itshould also be noted that in some alternative implementations, thefunctions noted in the blocks may occur out of the order. For example,two blocks shown in succession may in fact be executed substantiallyconcurrently or the blocks may sometimes be executed in the reverseorder, depending upon the functionality involved.

In this case, the term “unit”, as used herein, means, but is not limitedto, a software or hardware component, such as field programmable gatearray (FPGA) or application specific integrated circuit (ASIC), whichperforms certain tasks. However, the term “unit” is not meant to belimited to software or hardware. The term “unit” may advantageously beconfigured to reside on the addressable storage medium and configured toexecute on one or more processors. Thus, the term “unit” may include, byway of example, components, such as software components, object-orientedsoftware components, class components and task components, processes,functions, attributes, procedures, subroutines, segments of programcode, drivers, firmware, microcode, circuitry, data, databases, datastructures, tables, arrays, and variables. The functionality providedfor in the components and units may be combined into fewer componentsand units or further separated into additional components and units.Further, the components and units may be implemented to operate one ormore CPUs in a device or a security multimedia card. Further, in anembodiment, a unit may include one or more processors.

A wireless communication system was initially developed for the purposeof providing a voice-oriented service, but it has been expanded to, forexample, a broadband wireless communication system that provides ahigh-speed and high-quality packet data service together with thecommunication standards, such as 3GPP high speed packet access (HSPA),long term evolution (LTE) or evolved universal terrestrial radio access(E-UTRA), LTE-Advanced (LTE-A), 3GPP2 high rate packet data (HRPD),ultra-mobile broadband (UMB), and IEEE 802.16e. Also, for the 5thgeneration wireless communication system, 5G or NR communicationstandards have been developed.

In the NR system, which is a representative example of broadbandwireless communication systems, the downlink (DL) and uplink (UL) adoptorthogonal frequency division multiplexing (OFDM) schemes. Morespecifically, the DL adopts a cyclic-prefix OFDM (CP-OFDM) scheme, andthe UL adopts a discrete Fourier transform spreading OFDM (DFT-S-OFDM)scheme in addition to the CP-OFDM. The UL means a radio link in which aterminal (or user equipment (UE) or mobile station (MS)) transmits dataor a control signal to a base station (or gNodeB or base station (BS)),and the DL means a radio link in which the base station transmits dataor a control signal to the terminal. Such a multi-access scheme maydiscriminate data or control information of respective users from eachother by allocating and operating time-frequency resources on which thedata or control information of the respective users is to be carried sothat the time-frequency resources do not overlap each other, that is, soas to establish orthogonality.

The NR system adopts a hybrid automatic repeat request (HARQ) scheme inwhich a physical layer retransmits the corresponding data if decodingfailure occurs during an initial transmission. According to the HARQscheme, a receiver may transmit information (negative acknowledgement(NACK)) for notifying a transmitter of the decoding failure if thereceiver has not accurately decoded the data, and the transmitter maymake a physical layer retransmit the corresponding data. The receivermay combine the data that is retransmitted by the transmitter with theprevious data of which the decoding has failed to heighten the datareception performance. Further, if the receiver has accurately decodedthe data, the HARQ scheme may transmit information (acknowledgement(ACK)) for notifying of a decoding success to the transmitter, so thatthe transmitter can transmit new data.

FIG. 1 is a diagram illustrating the basic structure of a time-frequencydomain that is a radio resource region in which data or a controlchannel is transmitted on a downlink or an uplink in an NR system.

With reference to FIG. 1, a horizontal axis represents a time domain,and a vertical axis represents a frequency domain. In the time domain,the minimum transmission unit is an OFDM symbol, and N_(symb) OFDMsymbols 102 constitute one slot 106. The length of the subframe isdefined as 1.0 ms, and a radio frame is defined as 10 ms. In thefrequency domain, the minimum transmission unit is a subcarrier, and thetransmission bandwidth of the whole system is composed of N_(BW)subcarriers 104 in total.

In the time-frequency domain, the basic unit of resources is a resourceelement (RE) 112, which may be expressed by an OFDM symbol index and asubcarrier index. A resource block (RB) 108 or a physical resource block(PRB) is defined by N_(RB) contiguous subcarriers 110 in the frequencydomain. In general, the minimum transmission unit of data is the RB asdescribed above. In the NR system, N_(symb)=14 and N_(RB)=12, and N_(BW)is in proportion to the bandwidth of the system transmission band. Thedata rate may be increased in proportion to the number of RBs that arescheduled to the terminal.

For an FDD system that operates to discriminate a DL and an UL by meansof frequencies in the NR system, the DL transmission bandwidth and theUL transmission bandwidth may differ from each other. A channelbandwidth indicates an RF bandwidth corresponding to the systemtransmission bandwidth. Tables 1 and 2 present a part of thecorresponding relationship among the system transmission bandwidth thatis defined by the NR system in a frequency band that is lower than 6 GHzand in a frequency band that is higher than 6 GHz, subcarrier spacing,and channel bandwidth. For example, the NR system having 100 MHz channelbandwidth with 30 kHz subcarrier spacing has the transmission bandwidththat is composed of 273 RBs. Hereinafter, N/A may be abandwidth-subcarrier combination that is not supported by the NR system.

TABLE 1 Channel bandwidth BW_(Channel) Subcarrier 5 10 20 50 80 100[MHz] Spacing MHz MHz MHz MHz MHz MHz Transmission 15 kHz 25 52 106 270N/A N/A bandwidth 30 kHz 11 24  51 133 217 213 configuration 60 kHz N/A11  24  65 107  13 N_(RB)

TABLE 2 Channel bandwidth BW_(channel) Subcarrier [MHz] Spacing 50 MHz100 MHz 200 MHz 400 MHz Transmission  60 kHz 66 132 264 N/A bandwidth120 kHz 32 66 132 264 configuration N_(RB)

In the NR system, the frequency range may be dividedly defined by FR1and FR2 as shown in Table 3 below.

TABLE 3 Frequency Corresponding range frequency designation range FR1450 MHz-7125 MHz FR2 24250 MHz-52600 MHz

As described above, it may be possible that the range of the FR1 and FR2may be differently applied. For example, the frequency range of FR1 maybe changed and applied from 450 MHz to 6000 MHz.

In the NR system, scheduling information on DL data or UL data istransferred from the base station to the terminal through downlinkcontrol information (DCI). The DCI may be defined in accordance withvarious formats, and it may corresponds to whether the DCI is schedulinginformation on UL data (UL grant) or scheduling information on DL data(DL grant) according to each format, whether the DCI is compact DCIhaving a small size of control information, whether spatial multiplexingusing multiple antennas is applied, and whether the DCI is DCI for powercontrol. For example, DCI format 1-1 that is the scheduling controlinformation on the DL data (DL grant) may include at least one piece ofthe following control information.

-   -   Carrier indicator: indicating on which frequency carrier the        corresponding DCI is transmitted.    -   DCI format indicator: an indicator discriminating whether the        corresponding DCI is for a downlink or an uplink.    -   Bandwidth part (BWP) indicator: indicating from which BWP the        corresponding DCI is transmitted.    -   Frequency domain resource assignment: indicating the RB of the        frequency domain allocated to the data transmission. An        expressed resource is determined in accordance with the system        bandwidth and resource allocation scheme.    -   Time domain resource assignment: indicating from what OFDM        symbol of what slot a data related channel is to be transmitted.    -   VRB-to-PRB mapping: indicating in which scheme a virtual RB        (VRB) index and a physical RB (PRB) index are mapped onto each        other.    -   Modulation and coding scheme (MCS): indicating a modulation        scheme and the size of a transport block that is data intended        to be transmitted.    -   HARQ process number: indicating a process number of HARQ.    -   New data indicator: indicating whether HARQ is initially        transmitted or retransmitted.    -   Redundancy version: indicating a redundancy version of HARQ.    -   Transmit power control (TCP) command for a physical uplink        control channel (PUCCH): indicating a transmission power control        command for PUCCH that is an uplink control channel.

For data transmission through a physical uplink shared channel (PUSCH),as described above, the time domain resource assignment may betransferred by information on a slot on which the PUSCH is transmitted,a start OFDM symbol location S on the corresponding slot, and the numberL of symbols onto which the PUSCH is mapped. As described above, thelocation S may be a relative location from the start of the slot, L maybe the number of contiguous symbols, and S and L may be determined by astart and length indicator value (SLIV) defined as follows.

if ^((L − 1) ≤7) then ^( SLIV = 14·(L − 1) + S) else^( SLIV = 14·(14 − L + 1) + (14 − 1 − S)) where ^(0 < L ≤14 − S)

In the NR system, the terminal can be configured with information on theSLIV value, the PUSCH mapping type, and the PUSCH transmission slot inone row through radio resource control (RRC) configuration (e.g., theabove-described information may be configured in the form of a table).Thereafter, in the time domain resource assignment of the DCI, the basestation can transfer the information on the SLIV value, the PUSCHmapping type, and the PUSCH transmission slot to the terminal byindicating index values in the configured table.

In the NR system, type A and type B have been defined as the PUSCHmapping type. According to the PUSCH mapping type A, the first symbol ofDMRS symbols is located on the second or third OFDM symbol of the slot.According to the PUSCH mapping type B, the first symbol of the DMRSsymbols is located on the first OFDM symbol in the time domain resourceallocated through the PUSCH transmission.

The PUSCH resource mapping method, as described above, may also beapplied to the downlink data transmission through the physical downlinkshared channel (PDSCH) in a similar manner. In the NR system, the PDSCHmapping type may be defined as type A and type B, and particularly inthe mapping type B, the first symbol of the DMRS symbols may be locatedon the first symbol of the PDSCH.

The DCI may pass through a channel coding and modulation process, andmay be transmitted on a PUCCH that is a downlink physical controlchannel. Herein, the control information being transmitted on the PDCCHor PUCCH may be expressed as a case in which the PDCCH or PUCCH istransmitted. In the same manner, the data being transmitted on the PUSCHor PDSCH may be expressed as a case in which the PUSCH or PDSCH istransmitted.

In general, the DCI is scrambled with a specific radio network temporaryidentifier (RNTI) (or terminal identifier) independently of respectiveterminals to be added with a CRC, is channel-coded, and then isconfigured as independent PDCCHs to be transmitted. The PDCCH is mappedonto a control resource set (CORESET) configured to the terminal to betransmitted.

The downlink data may be transmitted on a PDSCH that is a physicalchannel for downlink data transmission. The PDSCH may be transmittedafter a control channel transmission interval, and schedulinginformation, such as a detailed mapping location in the frequency domainand a modulation scheme, is determined based on the DCI beingtransmitted on the PDCCH.

Through the MCS among the control information constituting the DCI, thebase station notifies the terminal of a modulation scheme applied to thePDSCH intended to be transmitted to the terminal and the size of data(transport block size (TBS)) intended to be transmitted. The MCS may becomposed of 5 bits or more or less. The TBS corresponds to the size ofthe data (transport block (TB)) that the base station intends totransmit before the channel coding for error correction is appliedthereto.

Herein, the TB may include a medium access control (MAC) header, a MACcontrol element (CE), one or more MAC service data units (SDUs), andpadding bits. Further, the TB may indicate a data unit being deliveredfrom the MAC layer to the physical layer or a MAC protocol data unit(PDU).

The modulation scheme that is supported in the NR system may bequadrature phase shift keying (QPSK), 16 quadrature amplitude modulation(16 QAM), 64 QAM, and 256 QAM, and respective modulation orders Qmcorrespond to 2, 4, 6, and 8. That is, for the QPSK modulation, 2 bitsper symbol may be transmitted, and for the 16 QAM, 4 bits per symbol maybe transmitted. Further, for the 64 QAM, 6 bits per symbol may betransmitted, and for the 256 QAM, 8 bits per symbol may be transmitted.

FIGS. 2 and 3 are diagrams illustrating a state where data for eMBB,URLLC, and mMTC, which are services being considered in a 5G or NRsystem, are allocated with frequency-time resources.

With reference to FIGS. 2 and 3, it can be identified that frequency andtime resources are allocated for information transmission in therespective systems. FIG. 2 is a diagram illustrating frequency and timeresources allocated for information transmission in the NR system,according to an embodiment.

FIG. 2 illustrates that data for eMBB, URLLC, and mMTC are allocated ina whole system frequency band 200. If URLLC data 203, 205, and 207 isgenerated while eMBB 201 and mMTC 209 are allocated and transmitted in aspecific frequency band, and transmission of the generated URLLC data isnecessary, the URLLC data 203, 205, and 207 may be transmitted withoutemptying or transmitting a portion in which the eMBB 201 and the mMTC209 have already been allocated. Because it is necessary to reduce alatency of the URLLC among the above-described services, the URLLC data203, 205, and 207 is allocated to a portion of the resource 201allocated to the eMBB to be transmitted. Of course, if the URLLC isadditionally allocated and transmitted on the eMBB-allocated resource,the eMBB data may not be transmitted on the redundant frequency-timeresources, and thus, the transmission performance of the eMBB data maybe lowered. An eMBB data transmission failure due to the URLLCallocation may occur.

FIG. 3 is a diagram illustrating frequency and time resources allocatedfor information transmission in the NR system, according to anotherembodiment.

In FIG. 3, respective subbands 302, 304, and 306 that are obtainedthrough division of a whole system frequency band 300 may be used forthe purpose of transmitting services and data. Information related tosubband configuration may be predetermined, and this information may betransmitted from a base station to a terminal through higher signaling.Further, information related to the subbands may be optionally dividedby the base station or a network node, and services may be provided tothe terminal without transmission of separate subband configurationinformation to the terminal. FIG. 3 illustrates a state where thesubband 302 is used to transmit eMBB data, the subband 304 is used totransmit URLLC data, and the subband 306 is used to transmit mMTC data.

The length of a transmission time interval (TTI) that is used for URLLCtransmission may be shorter than the length of the TTI that is used totransmit the eMBB or mMTC. Further, a response to the informationrelated to the URLLC may be transmitted earlier than that of the eMBB ormMTC, and thus, the information can be transmitted and received with alow latency. Physical layer channels used for respective types totransmit the three kinds of services or data as described above may havedifferent structures. For example, at least one of the TTI length,frequency resource allocation unit, control channel structure, and datamapping method may differ

Although three kinds of services and three kinds of data have beendescribed, more than three kinds of services and corresponding data mayexist, and even in such a case, the contents of the disclosure will beable to be applied.

In order to explain a method and an apparatus of the embodiments herein,the terms “physical channel” and “signal” in an NR system may be used.However, the contents of the disclosure may also be applied to awireless communication system that is not the NR system.

A sidelink (SL) is also referred to as a signal transmission/receptionpath between terminals, and may be interchangeably used with a PC5interface. Hereinafter, the base station is the subject that performsresource allocation to the terminal, and may be a base stationsupporting both vehicle-to-everything (V2X) communication and generalcellular communication or a base station supporting only V2Xcommunication. That is, the base station may mean an NR base station(gNB), LTE base station (eNB), or road site unit (RSU) (or fixedstation). The terminal may include user equipment, mobile station,vehicle supporting vehicular-to-vehicular communication (V2V), vehiclesupporting vehicular-to-pedestrian (V2P), pedestrian's handset (e.g.,smart phone), vehicle supporting vehicular-to-network communication(V2N), vehicle supporting vehicular-to-infrastructure communication(V2I), RSU mounted with a terminal function, RSU mounted with a basestation function, or RSU mounted with a part of a base station functionand a part of a terminal function. In the disclosure, a DL is a radiotransmission path of a signal that is transmitted from the base stationto the terminal, and an UL means a radio transmission path of a signalthat is transmitted from the terminal to the base station. Hereinafter,although the NR system is exemplified in embodiments of the disclosure,the embodiments of the disclosure can be applied to even other variouscommunication systems having similar technical backgrounds or channeltypes. Further, the embodiments of the disclosure may also be applied toother communication systems through partial modifications thereof in arange that does not greatly deviate from the scope of the disclosure bythe judgment of those skilled in the art.

In the disclosure, the terms “physical channel” and “signal” in therelated art may be interchangeably used with data or a control signal.For example, although the PDSCH is a physical channel on which data istransmitted, it may be called data in the disclosure.

Hereinafter, in the disclosure, higher signaling is a signal transfermethod in which the base station transfers a signal to the terminalusing a downlink data channel of a physical layer, or the terminaltransfers a signal to the base station using an uplink data channel ofthe physical layer, and it may also be mentioned as RRC signaling or MACCE.

In the following embodiments, a method and an apparatus for performingdata transmission/reception between the base station and the terminal orbetween the terminals are provided. Data may be transmitted from oneterminal to a plurality of terminals, or data may be transmitted fromone terminal to one terminal. Further, data may be transmitted from abase station to a plurality of terminals. However, the data transfer isnot limited thereto, but the disclosure will be able to be applied tovarious cases.

FIG. 4 is a diagram illustrating a process in which one transport blockis divided into several code blocks and CRCs are added thereto,according to an embodiment.

With reference to FIG. 4, a CRC 403 is added to the last or head portionof one TB 401 intended to be transmitted on an uplink or a downlink. TheCRC 403 may be composed of 16 bits, 24 bits, or a prefixed bit number,or may be composed of a variable bit number in accordance with channelsituations. The CRC 403 may be used to determine whether channel codinghas succeeded. A block including the TB 401 and the CRC 403 addedthereto is divided into several code blocks (CBs) 407, 409, 411, and413, in operation 405. The divided code blocks may have predeterminedmaximum sizes, and the last code block 413 may have a size that issmaller than the size of other code blocks 407, 409, and 411. However,this is merely exemplary, and according to another example, the lastcode block 413 may be set to have the same length as the length of othercode blocks 407, 409, and 411 through insertion of 0, a random value, or1 into the last code block 413. CRCs 417, 419, 421, and 423 arerespectively added to the code blocks 407, 409, 411, and 413, atoperation 415. The CRC may be composed of 16 bits, 24 bits, or aprefixed bit number, and may be used to determine whether channel codinghas succeeded.

In order to create the CRC 403, the TB 401 and a cyclic generatorpolynomial may be used, and the cyclic generator polynomial may bedefined in various methods. For example, if it is assumed that a cyclicgenerator polynomial for the CRC of 24 bits isgCRC24A(D)=D²⁴+D²³+D¹⁸+D¹⁷+D¹⁴+D¹¹+D¹⁰+D⁷+D⁶+D⁵+D⁴+D³+D+1, and L isL=24, with respect to TB data a₀, a₁, a₂, a₃, . . . . , a_(A−1), CRC p₀,p₁, p₂, p₃, . . . , p_(L−1) may be determined as a value obtained bydividing a₀D^(A+23)+a₁D^(A+22)+ . . . +a_(A−1)D²⁴+p_(a)+D²³+p₁D²²+ . . .+p₂₂D¹+p₂₃ by gCRC24A(D) with a remainder of 0. In the above-describedexample, although it is assumed that the CRC length L is 24, the CRClength L may be determined to include various lengths, such as 12, 16,24, 32, 40, 48, 64, and the like.

After the CRC is added to the TB in the process as described above, theTB is divided into N CBs 407, 409, 411, and 413. CRCs 417, 419, 421, and423 are added to the divided CBs 407, 409, 411, and 413, respectively,at operation 415. The CRC added to the CB may have a length that isdifferent from the length of the CRC added to the TB, or another cyclicgenerator polynomial may be used. However, the CRC 403 added to the TBand the CRCs 417, 419, 421, and 423 added to the code blocks may beomitted depending on the kind of channel code that is to be applied tothe code blocks. For example, if an LDPC code, rather than a turbo code,is to be applied to the code blocks, the CRCs 417, 419, 421, and 423 tobe inserted into the respective code blocks may be omitted.

However, even when the LDPC is applied, the CRCs 417, 419, 421, and 423may be added to the code blocks as they are. Further, even when a polarcode is used, the CRCs may be added or omitted.

As described above with reference to FIG. 4, in the TB intended to betransmitted, the maximum length of one code block may be determined inaccordance with the kind of the applied channel coding, and inaccordance with the maximum length of the code blocks, division of theTB and the CRC added to the TB into the code blocks may be performed.

In an LTE system, a CRC for a CB is added to a divided CB, and data bitsof the CB and the CRC are encoded with a channel code to determine codedbits, and as pre-engaged with respect to the respective coded bits, thenumber of the rate-matched bits may be determined.

In an NR system, the size of the TB may be calculated through thefollowing steps.

Step 1: In one PRB within an allocated resource, N_(RE)′ that is thenumber of REs allocated to PDSCH mapping is calculated.

Here, N_(RB)′ may be calculated by N_(sc) ^(RB)·N_(symb) ^(sh)−N_(DMRS)^(PRB)−N_(oh) ^(PRB). Here, N_(sc) ^(RB) is 12, and N_(symb) ^(sh) mayindicate the number of OFDM symbols allocated to the PDSCH. N_(DMRS)^(PRB) is the number of REs in one PRB occupied by a DMRS of a CDMgroup. N_(oh) ^(PRB) is the number of REs occupied by an overhead in onePRB configured through higher signaling, and may be configured to one of0, 6, 12, and 18. Thereafter, the total number N_(RE) of REs allocatedto the PDSCH may be calculated. Here, N_(RE) is calculated as min(156,N_(RR)′)·n_(PRB), and n_(PRB) indicates the number of PRBs allocated tothe terminal.

Step 2: The number N_(info) of temporary information bits may becalculated as N_(RE)*R*Q_(m)*v. Here, R is a code rate, Q_(m) is amodulation order, and information of these values may be transferredusing a table pre-engaged with an MCS bit field in control information.Further, v is the number of allocated layers. If N_(info)≤3824 a TBS maybe calculated through step 3 below. Otherwise, the TBS may be calculatedthrough step 4.

Step 3: N_(info)′ may be calculated through formulas of

$N_{info}^{\prime} = {\max \left( {24,{2^{n}*\left\lfloor \frac{N_{info}}{2_{n}} \right\rfloor}} \right)}$

and n=max(3,└log₂(N_(info))┘−6). The TBS may be determined as a valuethat is closest to N_(info)′ among values that are not smaller thanN_(info)′ in Table 4 below.

TABLE 4 Index TBS 1 24 2 32 3 40 4 48 5 56 6 64 7 72 8 80 9 88 10 96 11104 12 112 13 120 14 128 15 136 16 144 17 152 18 160 19 168 20 176 21184 99 192 23 208 24 224 25 240 26 256 27 272 28 288 29 304 30 320 31336 32 352 33 368 34 384 35 408 36 432 37 456 38 480 39 504 40 528 41552 42 576 43 608 44 640 45 672 46 704 47 736 48 768 49 808 50 848 51888 52 928 53 984 54 1032 55 1064 56 1128 57 1160 58 1192 59 1224 601256 61 1268 62 1326 63 1352 64 1416 65 1480 66 1544 67 1608 68 1672 691736 70 1800 71 1864 72 1928 73 2024 74 3038 75 2152 76 2216 77 2280 783408 79 9479 80 2536 81 2600 82 2664 83 2728 84 2792 85 2856 86 2976 873104 88 3240 89 3368 90 3496 91 3624 92 3752 93 3824

Step 4: N_(info)′ may be calculated through formulas of

$N_{info}^{\prime} = {\max \left( {3840,{2^{n} \times {round}\mspace{14mu} \left( \frac{N_{info} - 24}{2_{n}} \right)}} \right)}$

and n=└log₂(N_(info)−24)┘−5. The TBS may be determined through N_(info)′value and [pseudo-code 1] below.

Pseudo-code 1  if R ≤ 1/4   ${{TBS}\; = {{8*C*\left\lceil \frac{N_{\inf \mspace{14mu} o}^{\prime} + 24}{8*C} \right\rceil} - 24}},{{{where}\mspace{14mu} C} = \left\lceil \frac{N_{\inf \mspace{14mu} o}^{\prime} + 24}{3816} \right\rceil}$ else   if N_(inf o) ^(′) > 8424    ${{TBS}\; = {{8*C*\left\lceil \frac{N_{\inf \mspace{14mu} o}^{\prime} + 24}{8*C} \right\rceil} - 24}},{{{where}\mspace{14mu} C} = \left\lceil \frac{N_{\inf \mspace{14mu} o}^{\prime} + 24}{8424} \right\rceil}$  else    ${TBS}\; = {{8*\left\lceil \frac{N_{\inf \mspace{14mu} o}^{\prime} + 24}{8} \right\rceil} - 24}$  end if  end if

If one CB is inputted to an LDPC encoder in an NR system, parity bitsmay be added to the CB to be outputted. The quantity of parity bits maydiffer in accordance with an LDCP base graph. A method for sending allparity bits created by LDPC coding with respect to a specific input maybe called full buffer rate matching (FBRM). A method for limiting thenumber of transmittable parity bits may be called a limited buffer ratematching (LBRM). If resources are allocated for data transmission, anLDPC encoder output is made as a circular buffer, and bits of the madebuffer are repeatedly transmitted to the extent of the allocatedresources. The length of the circular buffer may be N_(cb). If thenumber of all parity bits being created by the LDPC coding is N, thelength of the circular buffer becomes N_(cb)=N in the FBRM method.

In the LBRM method, N_(cb) becomes min(N, N_(ref)), N_(ref) is given as

$\left\lfloor \frac{{TBS}_{LBRM}}{C \cdot R_{LBRM}} \right\rfloor,$

and R_(LBRM) may be determined as 2/3. In order to obtain TBS_(LBRM),the above-described method for obtaining the TBS, and the maximum numberof layers supported by the terminal in the corresponding cell and themaximum modulation order configured to the terminal in the correspondingcell may be assumed, and 64 QAM may be assumed in case that the maximummodulation order is not configured. Further, it may be assumed that thecode rate is 948/1024 that is the maximum code rate, N_(RE) is156·n_(PRB), and n_(PRB) is n_(PRB,LBRM). Here, n_(PRB,LMRM) may begiven as in Table 5 below.

TABLE 5 Maximum number of PRBs across all configured BWPs of a carriern_(PRB,LBRM) Less than 33 32 33 to 66 66 67 to 107 107 108 to 135 135136 to 162 162 163 to 217 217 Larger than 217 273

In the NR system, the maximum data rate supported by the terminal may bedetermined through mathematical Equation (1) below.

$\begin{matrix}{{{data}\mspace{14mu} {rate}\mspace{14mu} \left( {{in}\mspace{14mu} {Mbps}} \right)} = {1{0^{- 6} \cdot {\underset{j = 1}{\sum\limits^{J}}\left( {v_{Layers}^{(j)} \cdot Q_{m}^{(j)} \cdot f^{(j)} \cdot R_{\max} \cdot \frac{N_{PRB}^{{{BW}{(j)}}\mu} \cdot 12}{T_{s}^{\mu}} \cdot \left( {1 - {OH}^{(j)}} \right)} \right)}}}} & (1)\end{matrix}$

In Equation (1), J is the number of carriers tied through carrieraggregation, R_(max)=948/1024, v_(Layers) ^((j)) is the maximum numberof layers, Q_(m) ^((j)) is the maximum modulation order, f^((j)) is ascaling index, μ is a subcarrier spacing. Here, f^((j)) is one value of1, 0.8, 0.75, and 0.4, which can be reported by the terminal, and μ maybe given as in Table 6 below.

TABLE 6 Δƒ = 2^(μ) · Cyclic μ 15 [kHz] prefix 0 15 Normal 1 30 Normal 260 Normal, Extended 3 120 Normal 4 240 Normal

Further, T_(s) ^(μ) is an average OFDM symbol length, T_(s) ^(μ) may becalculated as

$\frac{10^{- 3}}{14 \cdot 2^{u}},$

and N_(PRM) ^(BW(j),μ) is the maximum number of RBs in BW(j). Further,is an overhead value, which may be given as 0.14 in a downlink of FR1(not higher than 6 GHz band) and may be given as 0.18 in an uplink, andwhich may be given as 0.08 in a downlink of FR2 (higher than 6 GHz band)and may be given as 0.10 in an uplink. The maximum data rate in thedownlink in the cell having 100 MHz frequency bandwidth in 30 kHzsubcarrier spacing through the Equation (1) may be calculated as inTable 7 below.

TABLE 7

Rmax

data rate 1   4 8 0.92578125 273 3.57143E-05 0.14 2337.0 0.8 4 80.92578125 273 3.57143E-05 0.14 1869.6  0.75 4 8 0.92578125 2733.57143E-05 0.14 1752.8 0.4 4 8 0.92578125 273 3.57143E-05 0.14  934.8

In contrast, the actual data rate that can be measured by the terminalin the actual data transmission may be a value obtained by dividing thedata amount by the data transmission time. This may be TBS in 1 TBtransmission, and may be a value obtained by dividing the sum of TB Ssby the TTI length in 2 TB transmission. As an example, in the samemanner as the assumption to obtain Table 7 above, the maximum actualdata rate in the downlink in the cell having the 100 MHz frequencybandwidth in the 30 kHz subcarrier spacing may be determined as in Table8 below in accordance with the number of allocated PDSCH symbols.

TABLE 8 TTI data length rate

n

C TBS (ms) (Mbps)  3 8  28  7644  226453.5 12   225,280  27   225,4800.107143 2,104.48  4 8  40 10920  323505.0 13   319,488  38   319,7840.142857 2,238.49  5 8  52 14196  420556.5 13   417,792  50   417,9760.178571 2,340.67  6 8  64 17472  517608.0 13   516,096  62   516,3120.214230 2,409.46  7 8  76 20748  614659.5 14   622,592  74   622,7600.250000 2,491.04  8 8  38 24024  711711.0 14   704,512  84   704,9040.285714 2,407.16  9 8 100 27300  808762.5 14   802,816  90   803,3040.321429 2,499.17 10 8 112 30576  905814.0 14   901,120 107   901,3440.357143 2,523.76 11 8 124 33852 1002805.5 14   999,424 119   999,5760.392357 2,544.38 12 8 136 37128 1099017.2 15 1,114,112 133 1,115,0480.428571 2,601.78 13 8 148 40404 1195068.5 15 1,212,416 144 1,213,0320.464286 2,612.68 14 8 100 43680 1294020.0 15 1,277,952 152 1,277,9920.500000 2,555.98

Through Table 7, it is possible to identify the maximum data ratesupported by the terminal, and through Table 8, it is possible toidentify the actual data rate following the allocated TBS. The actualdata rate may be higher than the maximum data rate in accordance withscheduling information.

In a wireless communication system, and particularly, in an NR system,the data rate that can be supported by the terminal may be pre-engagedbetween the base station and the terminal. This may be calculated usingthe maximum frequency band supported by the terminal, the maximummodulation order, and the maximum number of layers. However, thecalculated data rate may be different from the value calculated from theTBS being used for the actual data transmission and the length of theTTI.

Accordingly, the terminal may be allocated with a TBS that is largerthan the value corresponding to the data rate supported by the terminalitself, and to prevent this, there may be limitations in schedulable TBSin accordance with the data rate supported by the terminal.

FIG. 5A is a diagram illustrating one-to-one communication, that is,unicast communication, performed between two terminals through asidelink, according to an embodiment.

FIG. 5A illustrates a signal 503 transmitted from a first terminal 501to a second terminal 505, and the direction of the signal transmissionmay be opposite to the above-described direction. That is, the signalmay be transmitted from the second terminal 505 to the first terminal501. Other terminals 507 and 509 are unable to receive the signal beingexchanged through the unicast communication between the first terminal501 and the second terminal 505. The signal exchange through the unicastbetween the first terminal 501 and the second terminal 505 may includeprocesses of mapping resources engaged between the first terminal 501and the second terminal 505, scrambling using an engaged value, controlinformation mapping, data transmission using a configured value, andidentifying inherent ID values. The terminal may be a terminal thatmoves together with a vehicle. For the unicast, transmission of separatecontrol information, physical control channel, and data may beperformed.

FIG. 5B is a diagram illustrating a groupcast communication in which oneterminal transmits common data to a plurality of terminals through asidelink, according to an embodiment.

FIG. 5B illustrates a first terminal 551 transmitting common data toother terminals 553, 555, 557, and 559 in a groupcast 561 through asidelink, and other terminals 561 and 563 which are not included in thegroup are unable to receive signals being transmitted for the groupcast561.

The terminal that transmits the signal for the groupcast may be anotherterminal in the group, and resource allocation for the signaltransmission may be provided by the base station, may be provided by theterminal that serves as a leader in the group, or may be selected by theterminal that transmits the signal. The terminal may be a terminal thatmoves together with a vehicle. For the groupcasting, transmission ofseparate control information, physical control channel, and data may beperformed.

FIG. 6 is a diagram illustrating a process in which terminals havingreceived common data through groupcasting transmit information relatedto data reception success or failure to a terminal having transmittedthe data, according to an embodiment. With reference to FIG. 6,terminals 603, 605, 607, and 609, having received the common datathrough the groupcasting, transmit the information related to the datareception success or failure to a terminal 601 having transmitted thedata. The information may be HARQ-ACK feedback 611. Further, theterminals may be terminals having LTE-based sidelink or NR-basedsidelink function. The terminal having only the LTE-based sidelinkfunction may be unable to transmit/receive NR-based sidelink signal anda physical channel. The sidelink may be interchangeably used with PC5,V2X, or D2D. In FIGS. 5B and 6, the transmission/reception in accordancewith the groupcasting is exemplified, but it may also be applied tounicast signal transmission/reception between the terminals.

FIG. 7 is a diagram illustrating a state in which a synchronizationsignal of an NR system and a PBCH are mapped onto each other in thefrequency and time domain, according to an embodiment.

A primary synchronization signal (PSS) 701, a secondary synchronizationsignal (SSS) 703, and a PBCH 705 are mapped onto each other over 4 OFDMsymbols. The PSS 701 and the SSS 703 are mapped onto 12 RBs, and thePBCH 705 is mapped onto 20 RBs. It is illustrated in the table of FIG. 7how the frequency bands of 20 RBs are varied in accordance with asubcarrier spacing (SCS). A resource region on which the PSS 701, SSS703, and PBCH 705 are transmitted may be referred to as an SS/PBCHblock. Further, the SS/PBCH block may be referred to as an SSB block.

FIG. 8 is a diagram illustrating what symbols one SS/PBCH block ismapped onto in a slot, according to an embodiment.

FIG. 8 illustrates an LTE system using a subcarrier spacing of 15 kHzand an NR system using a subcarrier spacing of 30 kHz. SS/PBCH blocks811, 813, 815, and 817 of the NR system are transmitted in locations801, 803, 805, and 807 in which cell-specific reference signals (CRS)being always transmitted in the LTE system can be avoided. This allowsthe LTE system and the NR system to coexist in one frequency band.

FIG. 9 is a diagram illustrating symbols on which SS/PBCH blocks can betransmitted in accordance with subcarrier spacing, according to anembodiment.

With reference to FIG. 9, the subcarrier spacing may be configured as 15kHz, 30 kHz, 120 kHz, and 240 kHz, and in accordance with the subcarrierspacing, the location of a symbol in which an SS/PBCH block (or SSBblock) can be located may be determined. FIG. 9 illustrates the symbollocation in which the SSB in accordance with the subcarrier spacing canbe transmitted on each symbol within 1 ms, and it is not necessary forthe SSB to always be transmitted in the region indicated in FIG. 9.Accordingly, the location in which the SSB block is transmitted may beconfigured in the terminal through system information or dedicatedsignaling.

FIG. 10 is a diagram illustrating symbols on which SS/PBCH blocks can betransmitted in accordance with subcarrier spacing, according to anotherembodiment.

With reference to FIG. 10, the subcarrier spacing may be configured as15 kHz, 30 kHz, 120 kHz, and 240 kHz, and in accordance with thesubcarrier spacing, the location of a symbol in which an SS/PBCH block(or SSB block) can be located may be determined. FIG. 10 illustrates asymbol location 1009 in which the SSB block, in accordance with thesubcarrier spacing, can be transmitted on each symbol within 5 ms, andthe location in which the SSB block is transmitted may be configured inthe terminal through system information or dedicated signaling. It isnot necessary for the SS/PBCH block to always be transmitted in theregion in which the SS/PBCH block can be transmitted, and the SS/PBCHblock may be or may not be transmitted depending on the selection of thebase station. Accordingly, the location in which the SSB block istransmitted may be configured in the terminal through the systeminformation or the dedicated signaling.

Herein, a sidelink control channel may be referred to as a physicalsidelink control channel (PSCCH), and a sidelink shared channel or adata channel may be referred to as a physical sidelink shared channel(PSSCH). Further, a broadcast channel that is broadcasted together witha synchronization signal may be referred to as a physical sidelinkbroadcast channel (PSBCH), and a channel for feedback transmission maybe referred to as a physical sidelink feedback channel (PSFCH). However,the feedback transmission may be performed using the PSCCH or PSSCH. Inaccordance with the transmitting communication system, the channel maybe referred to as LTE-PSCCH, LTE-PSSCH, NR-PSCCH, or NR-PSSCH. Herein, asidelink means a link between terminals, and a Uu link means a linkbetween a base station and a terminal.

FIG. 11 is a diagram illustrating a resource pool that is defined as aset of resources on time and frequency being used for sidelinktransmission and reception, according to an embodiment.

A resource pool 1110 is non-contiguously allocated on time andfrequency. Herein, although explanation has been made focused on a casein which a resource pool is non-contiguously allocated on frequency, theresource pool can also be contiguously allocated on the frequency.

“A non-contiguous resource allocation 1120 is performed on thefrequency. The granularity of resource allocation on the frequency maybe a PRB.

A resource allocation 1121 on the frequency is performed based on asub-channel. The sub-channel may be defined in the unit on the frequencycomposed of a plurality of RBs. The sub-channel may be defined as aninteger multiple of the RB. The resource allocation 1121 denotes asub-channel composed of four contiguous PRBs. The size of thesub-channel may be differently configured, and although it is generalthat one sub-channel is composed of contiguous PRBs, it is not necessarythat the sub-channel is composed of the contiguous PRBs. The sub-channelmay become the basic unit of resource allocation on a PSSCH or PSCCH,and thus, the size of the sub-channel may be differently configureddepending on whether the corresponding channel is the PSSCH or PSCCH.Further, the term “sub-channel” may be replaced by another term, such asa RBG.

A start location of a sub-channel on the frequency in a resource poolis, startRB Subchanel 1122.

The resource block that is a frequency resource that belongs to aresource pool for the PSSCH in an LTE V2X system may be determined inthe following method.

-   -   The resource block pool consists of N_(subcH) sub-channels where        N_(subcH) is given by higher layer parameter numSubchannel.    -   The sub-channel m for m=0, 1, . . . , N_(subCH)−1 consists of a        set of n_(subCHsize) contiguous resource blocks with the        physical resource block number        n_(PRB)=n_(subCHRBstart)+m*n_(subCHsize)+j for j=0, 1, . . . ,        n_(subCHsize)−1 where n_(subCHRBstart) and n_(subCHsize) are        given by higher layer parameters startRBSubchannel and        sizeSubchannel, respectively

Non-contiguous resource allocation 1130 is performed on time. Thegranularity of resource allocation on time may be a slot. Herein,although the resource pool is non-contiguously allocated on the time,the resource pool can also be contiguously allocated on the time.

A start location of a slot on time is startSlot 1131. Subframes (t₀^(SL), t₁ ^(SL), . . . , t_(T) _(MAX) ^(SL)) that are time resourcesthat belong to the resource pool for the PSSCH in the LTE V2X system maybe determined in the following method.

-   -   0≤t_(i) ^(SL)<10240    -   the subframe index is relative to subframe #0 of the radio frame        corresponding to SFN 0 of the serving cell or DFN 0,    -   the set includes all the subframes except the following        subframes,        -   subframes in which SLSS resource is configured,        -   downlink subframes and special subframes if the sidelink            transmission occurs in a TDD cell,        -   reserved subframes which are determined by the following            steps:        -   1) the remaining subframes excluding N_(slss) and N_(dssf)            subframes from the set of all the subframes are denoted by            (l₀, l₁, . . . , l_((10240−N) _(slss) _(−N) _(dssf) ⁻¹⁾)            arranged in increasing order of subframe index, where            N_(slss) is the number of subframes in which SLSS resource            is configured within 10240 subframes and N_(dssf) is the            number of downlink subframes and special subframes within            10240 subframes if the sidelink transmission occurs in a TDD            cell.        -   2) a subframe l_(r) (0≤r<(10240−N_(slss)−N_(dssf))) belongs            to the reserved subframes if

$r = \left\lfloor \frac{m \cdot \left( {10240 - N_{slss} - N_{dssf}} \right)}{N_{reserved}} \right\rfloor$

where m=0, . . . , N_(reserved)−1 andN_(reserved)=(10240−N_(slss)−N_(dssf))mod L_(bitmap). Here, L_(bitmap)the length of the bitmap is configured by higher layers.

-   -   the subframes are arranged in increasing order of subframe        index.        -   A bitmap (b₀, b₁, . . . , b_(L) _(bitmap) ⁻¹) associated            with the resource pool is used where L_(bitmap) the length            of the bitmap is configured by higher layers.        -   A sub frame t_(k)            ^(sL)(0≤k<(10240−N_(slss)−N_(dssf)−N_(reserved))) belongs to            the subframe pool if b_(k′)=1 where k′=k mod L_(bitmap).

FIG. 12 is a diagram illustrating a scheduled resource allocation (mode1) method in a sidelink, according to an embodiment. The scheduledresource allocation (mode 1) is a method in which a base stationallocates resources being used for sidelink transmission in a dedicatedscheduling method to RRC-connected terminals. The base station canmanage the resources of the sidelink, and thus, it may be effective inperforming interference management and resource pool management.

In FIG. 12, a terminal 1201 camps on, at 1205, and receives a sidelinksystem information block (SL SIB) from a base station 1203, at 1210. Thesystem information may include resource pool information fortransmission/reception, configuration information for a sensingoperation, information for synchronization configuration, andinformation for inter-frequency transmission/reception. If data trafficfor V2X is created, the terminal 1201 performs an RRC connection withthe base station, at 1220. The RRC connection between the terminal andthe base station may be called a Uu-RRC. The above-described Uu-RRCconnection process may be performed before the data traffic is created.

The terminal 1201 requests the base station to provide a transmissionresource for performing V2X communication, at 1230. The terminal 1201may request the transmission resource from the base station using an RRCmessage or a MAC CE. A SidelinkUElnformation or UEAssistanceInformationmessage may be used as the RRC message. The MAC CE may be, for example,a buffer status report MAC CE of a new format (including at least anindicator notifying of a buffer status report for V2X communication orinformation on the size of data being buffered for D2D communication).With respect to the detailed format and the contents of the bufferstatus report being used in the 3GPP, the 3GPP standards TS36.321“E-UTRA MAC Protocol Specification” are referred to. The base station1203 allocates the V2X transmission resource to the terminal 1201through a dedicated Uu-RRC message. This message may be included in anRRCConnectionReconfiguration message. The allocated resource may be aV2X resource through the Uu or a resource for PC5 depending on the kindof traffic requested by the terminal or the congestion degree of thecorresponding link. For the above-described determination, the terminalmay additionally send ProSe per packet priority (PPPP) or logicalchannel ID information of the V2X traffic throughUEAssistanceInformation or MAC CE.

Because the base station is also aware of information on resources beingused by other terminals, the base station allocates a remaining resourcepool among the resources requested by the terminal 1201, at 1235. Thebase station may indicate the final scheduling to the terminal 1201 bymeans of DCI transmission through the PDCCH, at 1240.

For broadcast transmission, the terminal 1201 broadcasts sidelinkcontrol information (SCI) to other terminals 1202 on the PSCCH withoutadditional RRC configuration of the sidelink, at 1260. Further, theterminal 1201 may broadcast data to other terminals 1202 on the PSSCH,at 1270.

In contrast with this, for unicast and groupcast transmission, theterminal 1201 may perform the RRC connection with other terminals in aone-to-one manner. Here, for discrimination against the Uu-RRC, the RRCconnection between the terminals may be referred to as a PC5-RRC. Evenin case of the groupcast, the PC5-RRC is individually connected betweenthe terminals in the group, at 1215. Although FIG. 12 illustrates thatthe connection of the PC5-RRC, at 1215, is performed after 1210, it maybe performed any time before 1210 or 1260.

If the RRC connection is necessary between the terminals, the terminal1201 performs the PC5-RRC connection of the sidelink, at 1215, andtransmits the SCI to other terminals 1202 on the PSCCH through theunicast and groupcast, at 1260. The groupcast transmission of the SCImay be construed as the group SCI. Further, the terminal 1201 transmitsdata to other terminals 1202 on the PSSCH through the unicast andgroupcast, at 1270.

FIG. 13 is a diagram illustrating a UE autonomous resource allocation(mode 2) method in a sidelink, according to an embodiment.

In the UE autonomous resource allocation (mode 2), the base stationprovides a sidelink transmission/reception resource pool for V2X assystem information, and the terminal selects the transmission resourcein accordance with a determined rule. The resource selection method maybe zone mapping or sensing based resource selection or random selection.In contrast with the scheduled resource allocation (mode 1) method inwhich the base station directly participates in the resource allocation,the UE autonomous resource allocation (mode 2) method of FIG. 13 isdifferent from the scheduled resource allocation (mode 1) method in thatthe terminal 1301 autonomously selects the resource based on theresource pool pre-received through the system information, and transmitsthe data.

In the V2X communication, a base station 1303 allocates various kinds ofresource pools (V2X resource pool and V2P resource pool) for a terminal1301. The resource pool may be composed of a resource pool on which theterminal can autonomously select an available resource pool aftersensing the resources being used by other neighboring terminals, and aresource pool on which the terminal randomly selects a resource from apredetermined resource pool.

The terminal 1301 camps on, at 1305, and receives an SL SIB from thebase station 1303, at 1310. The system information may include resourcepool information for transmission/reception, configuration informationfor a sensing operation, information for synchronization configuration,and information for inter-frequency transmission/reception. Theoperation illustrated in FIG. 13 differs greatly from the operationillustrated in FIG. 12 in that for FIG. 12, the base station 1203 andthe terminal 1201 operate in an RRC-connected state, whereas for FIG.13, they may operate even in an idle mode in which the RRC is notconnected. Further, even in the RRC-connected state, the base station1303 does not directly participate in the resource allocation, and mayoperate so that the terminal autonomously selects the transmissionresource. The RRC connection between the terminal and the base stationmay be referred to as Uu-RRC, at 1320. If data traffic for V2X iscreated, at 1330, the terminal 1301 selects the resource pool of thetime and/or frequency region in accordance with the transmissionoperation configured among the resource pools transferred from the basestation 1303 through the system information.

For the broadcast transmission, the terminal 1301 broadcasts the SCI toother terminals 1302 on the PSCCH through broadcasting withoutadditional RRC configuration of the sidelink, at 1350. Further, theterminal 1201 may broadcast data to other terminals 1302 on the PSSCH,at 1360.

In contrast, when the unicast and groupcast transmission, the terminal1301 may perform the RRC connection with other terminals in a one-to-onemanner, at 1315. Here, for discrimination against the Uu-RRC, the RRCconnection between the terminals may be called a PC5-RRC. Even in caseof the groupcast, the PC5-RRC is individually connected between theterminals in the group. This connection of the RRC layer in the sidelinkmay be called the PC5-RRC. Through the PC5-RRC connection, UE capabilityinformation for the sidelink may be exchanged between the terminals, orthe exchange of configuration information required for the signaltransmission/reception may be performed. Although FIG. 13 illustratesthat the connection of the PC5-RRC at 1315 is after 1310″, it may beperformed any time before 1310 or 1350.

If the RRC connection is necessary between the terminals, the terminal1301 performs the PC5-RRC connection of the sidelink, and transmits theSCI to other terminals 1302 on the PSCCH through the unicast andgroupcast, at 1350. The groupcast transmission of the SCI may beconstrued as the group SCI. Further, the terminal 1301 transmits data toother terminals 1302 on the PSSCH through the unicast and groupcast, at1360.

In order to effectively perform the sensing in a situation whereperiodic and aperiodic traffics coexist, sensing window A and sensingwindow B are defined.

FIG. 14A is a diagram illustrating a method for configuring sensingwindow A for UE autonomous resource allocation (mode 2) of a sidelink,according to an embodiment.

As illustrated in 1400 of FIG. 14A, when triggering for selecting atransmission resource occurs in slot n 1401, a sensing window A 1402 maybe defined as follows.

-   -   Sensing window A 1402 may be defined as a slot section of [n−T₀,        n−1]. Here, To may be determined as a fixed value, and may be        determined to be configurable.    -   As an example of a case in which T₀ is determined as a fixed        value, it may be indicated as T₀=1000*2^(μ) with respect to the        periodic traffic. In contrast, T₀ may be configured as a fixed        value of T₀=100*2^(μ) with respect to the aperiodic traffic. As        described above, the fixed T₀ value may be changed to another        value in accordance with the traffic characteristic being        considered, and may be fixed to the same value with respect to        the periodic and aperiodic traffics. Here, μ is an index        corresponding to numerology, and is configured as the following        values in accordance with the subcarrier spacing.    -   SCS=15 kHz, μ=0    -   SCS=30 kHz, μ=1    -   SCS=60 kHz, μ=2    -   SCS=120 kHz, μ=3    -   When T₀ is determined to be configurable, the configuration for        this may be indicated through the SL SIB or UE-specific higher        signaling. When indicated through the SL SIB, the corresponding        value may be configured within resource pool information among        the corresponding system information. If T₀ is configured within        the resource pool information, always constant T₀ is used within        the resource pool.    -   In the sensing window A 1402, SCI decoding and sidelink        measurement for another terminal may be performed.    -   The terminal that performs the sensing may acquire resource        allocation information for another terminal and QoS information        for a packet from the received SCI within the sensing window A        1402. The resource allocation information may include a        reservation interval for the resource. Further, the QoS        information may be latency, reliability, and priority        information in accordance with the minimum required        communication range for the transmitted traffic and data rate        requirements. Further, the terminal may acquire location        information of another terminal from the received SCI. The        terminal may calculate a TX-RX distance from the location        information of another terminal and its own location        information.    -   The terminal may measure a sidelink reference signal received        power (SL RSRP) from the received SCI within the sensing window        A 1402.    -   The terminal may measure a sidelink received signal strength        indicator (SL RSSI) within the sensing window A 1402.

The sensing window A 1402 may be used for the main purpose ofdetermining resources for the UE autonomous resource allocation (mode 2)through sensing of the periodic traffic. The terminal may grasp theperiodic resource allocation information of another terminal through theSCI decoding, and if the terminal determines that allocation of thetransmission resource to the resource to be used by another terminal isnot effective using the result of measuring the sidelink, such as the SLRSRP or SL RSSI, the corresponding resource may be excluded from aresource selection window 1403. As illustrated in FIG. 14A, when thetriggering for selecting the transmission resource occurs in slot n, at1401, the resource selection window 1403 may be defined as follows.

The resource selection window 1403 may be defined as a slot section of[n+T₁, n+T₂]. Here, T₁ and T₂ may be determined as fixed values or maybe determined to be configurable. In contrast, T₁ and T₂ may bedetermined in a fixed range, and the terminal may configure propervalues within the fixed range in consideration of the implementationthereof.

-   -   T₁ and T₂ may be determined in a fixed range, and in        consideration of the implementation thereof, the terminal may        configure proper values within the fixed range, for example, in        the range of T₁≤4 and 20≤T₂≤100.    -   A final transmission resource 1406 may be selected within the        resource selection window 1403 using the result of the sensing        performed in the sensing window A 1402.

When sensing is performed using only the sensing window A 1402 asillustrated in FIG. 14A, and the transmission resource selection isperformed through this, the following transmission resource selectionmethod may be used.

Transmission resource selection method-1

-   -   Step-1: The number M_(total) of resource candidates capable of        performing resource allocation is determined based on the        resource pool information within the resource selection window        1403.    -   Step-2: The terminal excludes resources of which the usage is        determined to be ineffective due to occupation by another        terminal within the resource selection window 1403 using the        sensing result in the sensing window A 1402, and remains        X(≤M_(total)) resource candidates capable of performing resource        allocation. For this, a method for excluding resources through        SCI decoding for another terminal and sidelink measurement may        be used.    -   Step-3: A resource candidate list X is reported to a higher        layer of the terminal, and the final transmission resource among        X candidates is randomly selected on the higher layer of the        terminal.

FIG. 14B is a diagram illustrating a method for configuring sensingwindow B for UE autonomous resource allocation (mode 2) of a sidelink,according to an embodiment. As illustrated in 1430 of FIG. 14B, whentriggering for selecting a transmission resource occurs in slot n 1401,sensing window B 1404 may be defined as follows.

-   -   Sensing window B 1404 may be defined as a slot section of        [n+T₁′, n+T₂′]. T₁′ and T₂′ may be determined as fixed values,        or may be determined to be configurable. In contrast, T₁′ and        T₂′ may be determined in a fixed range, and the terminal may        configure proper values within the fixed range in consideration        of the implementation thereof. Further, when k indicates the        slot in which the resource is finally selected, the sensing        window B is interrupted in k slot, and in this case, the sensing        window B becomes [n+T₁′, k].    -   T₁′ and T₂′ may be configured to have the same values as the        values of T₁ and T₂ of the resource selection window 1403 of        FIG. 14A, respectively, or may be configured to have different        values.    -   For example, if T₁′ is configured as T₁′=0, it means that        sensing is performed from a triggering slot n for selecting the        transmission resource.    -   By the configured T₁′ and T₁ values, the sensing window B may be        configured as one slot or more slots.    -   In the sensing window B 1404, the SCI decoding for another        terminal and sidelink measurement may be performed.    -   Sensing in the sensing window B 1404 is performed.

The sensing window B 1404 may be used for the purpose of determiningresources for UE autonomous resource allocation (mode 2) throughadditional sensing of periodic and aperiodic traffics with respect tothe sensing window A. In the sensing window B 1404 configuredhereinafter based on a triggering slot n for selecting the transmissionresource, it is possible to sense aperiodic traffic that is unable to bepredicted in the sensing window A 1402 using the sidelink measurementfor the slot to which an actual transmission resource can be allocated.The sensing through the sensing window B 1404 may be understood as anoperation of performing the sensing with respect to the traffic sensedfor each slot regardless of whether the traffic is periodic oraperiodic. When sensing is performed using the sensing window B 1404 asillustrated in FIG. 14B, and the transmission resource selection isperformed through this, the following transmission resource selectionmethod may be used.

-   -   Transmission resource selection method-2    -   Step-1: It is determined whether a corresponding resource is        idle by performing sensing in the corresponding slot within the        sensing window B 1404.    -   The resource allocation unit on frequency may be defined as A        (≥1) sub-channels or all sub-channels. The number N_(total) of        resource candidates capable of performing resource allocation        within the corresponding slot is determined in accordance with        the resource allocation unit on the frequency.    -   The sensing may be performed through SCI decoding and sidelink        measurement.    -   Step-2-1: If it is determined that the corresponding resource is        idle through the sensing in Step-1 as described above, the final        transmission resource 1406 among the number N_(total) of        resource candidates capable of performing resource allocation        within the corresponding slot is determined.    -   Step-2-2: If it is determined that all the corresponding        resources are busy through the sensing in Step-1 as described        above, the following operation may be selected.    -   If the next slot is also configured as the sensing window B        1404, the operation skips to the next slot, and Step-1 as        described above is performed.    -   If the next slot is not configured to the sensing window B 1404,        the following operation may be considered.    -   In the current slot, the final transmission resource 1406 is        determined using QoS information or the result of energy        detection. The QoS information may be priority information in        accordance with at least one of priority, latency, reliability,        proximity service PPPP, ProSe per-packet reliability (PPPR),        minimum required communication range for traffic being        transmitted, or data rate requirements. The priority may mean to        include the PPPP and the PPPR, and may be a value selected        within a range of predetermined values, and data that is        necessary to be transmitted in the sidelink may have one        priority value.    -   The transmission in the current slot may be canceled, and a        backoff operation may be performed.

As defined through FIGS. 14A and 14B, the sensing window A and thesensing window B may be divided based on a time point where triggeringfor selecting the transmission resource comes down. Specifically, basedon the triggering slot n for selecting the transmission resource, thepreviously configured sensing section may be defined as the sensingwindow A 1402, and the sensing section configured thereafter may bedefined as the sensing window B 1404.

FIG. 14C is a diagram illustrating a method for configuring sensingwindow A and sensing window B for UE autonomous resource allocation(mode 2) of a sidelink, according to an embodiment. In 1460 of FIG. 14C,sensing window A and sensing window B are simultaneously configured.When the triggering for selecting the transmission resource occurs inslot n 1401, the sensing window A 1402 and the sensing window B 1404 mayrefer to the above-described definition. When the sensing is performedusing both the sensing window A 1402 and sensing window B 1404, asillustrated in FIG. 14C, and the transmission resource selection isperformed, the following transmission resource selection method may beused.

-   -   Transmission resource selection method-3    -   Step-1: The number M_(total) of resource candidates capable of        performing resource allocation is determined based on the        resource pool information within the resource selection window        1403.    -   Step-2: The terminal performing the sensing excludes resources        of which the usage is determined to be ineffective due to        occupation by another terminal within the resource selection        window 1403 using the sensing result in the sensing window A        1402, and remains X (≤M_(total)) resource candidates capable of        performing resource allocation. SCI decoding for another        terminal and sidelink measurement may be used to exclude the        resources.    -   Step-3: A resource candidate list X is reported to a higher        layer of the terminal, and Y candidates among X candidates are        randomly down-selected on the higher layer of the terminal.    -   Step-4-1: If the sensing window B 1404 is included in the        resource selection window 1403, the terminal selects the final        transmission resource 1406 among Y candidates determined on the        higher layer by the transmission resource selection method-2        using the sensing result of the sensing window B 1404 on the        physical layer.    -   If the sensing window B 1404 is included in the resource        selection window 1403, this corresponds to a section of [n+T₁,        k] in FIG. 14C. Such a condition may be determined by the        configuration of T₁ and T₂, and T₁′ and T₂′.    -   Step-4-2: If the sensing window B 1404 is not included in the        resource selection window 1403, the final transmission resource        1406 is selected by the transmission resource selection method-2        using the sensing result in the sensing window B on the physical        layer.    -   When the sensing window B 1404 is not included in the resource        selection window 1403 corresponds to a section of [n+T₁′,        n+T₁−1] in FIG. 14C. Such a condition may be determined by the        configuration of T₁ and T₂, and T₁′ and T₂′.

In the transmission resource selection method-e, the selection of Ycandidates on the higher layer may be omitted, and the following methodmay be used.

-   -   Transmission resource selection method-4    -   Step-1: The number M_(total) of resource candidates capable of        performing resource allocation is determined based on the        resource pool information within the resource selection window        1403.    -   Step-2: The terminal performing the sensing excludes resources        of which the usage is determined to be ineffective due to        occupation by another terminal within the resource selection        window 1403 using the sensing result in the sensing window A        1402, and remains X (≤M_(total)) resource candidates capable of        performing resource allocation. SCI decoding for another        terminal and sidelink measurement may be used to exclude the        resources.    -   Step-3-1: If the sensing window B 1404 is included in the        resource selection window 1403, the terminal selects the final        transmission resource 1406 among X candidates by the        transmission resource selection method-2 using the sensing        result of the sensing window B 1404 on the physical layer.    -   If the sensing window B 1404 is included in the resource        selection window 1403, this corresponds to a section of [n+T₁,        k] in FIG. 14C. Such a condition may be determined by the        configuration of T₁ and T₂, and T₁′ and T₂′.    -   Step-3-2: If the sensing window B 1404 is not included in the        resource selection window 1403, the final transmission resource        1406 is selected by the transmission resource selection method-2        using the sensing result in the sensing window B on the physical        layer.    -   The sensing window B 1404 not being included in the resource        selection window 1403 corresponds to a section of [n+T₁′,        n+T₁−1] in FIG. 14C. Such a condition may be determined by the        configuration of T₁ and T₂, and T₁′ and T₂′.

If the sensing window A 1402 and the sensing window B 1404 aresimultaneously configured, the final resource selection may bedetermined by the resource selection window 1403 and the sensing windowB 1404. The transmission resource selection method-3 and thetransmission resource selection method-4 are methods for performing thesensing in a situation where the periodic and aperiodic traffics coexistby simultaneously configuring the sensing window A 1402 and the sensingwindow B 1404 and optimizing the selection of the transmission resourcethrough the sensing.

The sensing and the transmission resource selection in the UE autonomousresource allocation (mode 2) of the sidelink as described above may beimplemented in various methods. For example, when simultaneouslyconfiguring the sensing window A 1402 and the sensing window B 1404, ifthe triggering for selecting the transmission resource occurs in slot nin a state where the terminal is always performing the sensing for thesensing window A 1402, the terminal may be implemented to select thefinal transmission resource by sensing the sensing window B 1404.However, the terminal, which always performs the sensing for the sensingwindow A 1402, can immediately use the sensing result of the sensingwindow A 1402 anytime, and thus, it has the advantage on the side of thelatency in selecting the transmission resource, but it has thedisadvantage on the side of energy consumption.

Accordingly, as another method, the terminal may be implemented toimmediately perform the sensing for the sensing window A 1402 if atraffic to be transmitted occurs, and to select the final transmissionresource by performing the sensing for the sensing window B 1404 afterperforming triggering for selecting the transmission resource. Thelatter method has the advantage that it can minimize the energyconsumption of the terminal, but has the disadvantage on the side of thelatency in selecting the transmission resource.

From the foregoing, an example has been described, in which an emptyfrequency-time resource is searched for the communication between theterminals in the sidelink, and the signal is transmitted on the searchedresources. However, the method and the apparatus provided in thedisclosure are not limited thereto, and can be applied to variouschannel occupation and channel reservation methods.

FIG. 15 is a diagram illustrating a mode 1 method for performingsidelink data transmission through reception of scheduling informationfrom a base station as illustrated in FIG. 12, according to anembodiment. A method for receiving scheduling information from a basestation and performing sidelink communication based on the schedulinginformation is referred to as mode 1.

A terminal 1501 intended to perform transmission in a sidelink receivesscheduling information 1509 for sidelink communication from a basestation 1511. The terminal 1501 intended to perform transmission in thesidelink may be referred to as a transmitting terminal, and a terminal1503 performing data reception in the sidelink may be referred to as areceiving terminal. However, the transmitting terminal 1501 and thereceiving terminal 1503 may be able to perform both data transmissionand reception in the sidelink. The scheduling information 1509 for thesidelink communication may be obtained through reception of DCItransmitted by the base station 1511, and the DCI may include followinginformation.

-   -   Carrier indicator: used for the purpose of scheduling the        sidelink of another carrier in a situation where carrier        aggregation (CA) is applied.    -   Lowest index of sub-channel allocation for initial transmission:        used for frequency resource allocation of the initial        transmission.    -   Information to be included in sidelink control information        -   This may include frequency resource allocation information,            the frequency resource allocation information for initial            transmission and retransmission, and resource allocation for            subsequent N-times transmission or resource reservation            information.        -   Time interval information between initial transmission and            retransmission    -   This may include information on the sidelink slot structure, and        information on what slot and what symbols can be used for the        sidelink.    -   This may include HARQ-ACK/CSI feedback timing information, and        timing information for transmitting HARQ-ACK or CSI feedback in        the sidelink to the base station.    -   Addressee ID: ID information on what terminals are to receive        information    -   Quality-of-Service (QoS) information such as priority:        Information on what priority data is to be transmitted with

The scheduling may be used for one sidelink transmission, or may be usedfor periodic transmission, semi-persistent scheduling (SPS), orconfigured grant. The scheduling methods may be discriminated by anindicator included in the DCI, RNTI scrambled in a CRC added to the DCI,or ID value. Zero (0) bit may be additionally added to the DCI to makethe size of the DCI equal to the size of other DCI formats, such as DCIfor downlink scheduling or uplink scheduling.

The transmitting terminal 1501 receives the SCI for sidelink schedulingfrom the base station 1511, transmits a PSCCH including the sidelinkscheduling information 1507, and transmits a PSSCH that is thecorresponding data 1505. The sidelink scheduling information 1507 may beSCI, and the SCI may include the following information.

-   -   HARQ process number: HARQ process ID for HARQ-related operation        of data being transmitted.    -   New data indicator (NDI): Information on whether the currently        transmitted data is new data.    -   Redundancy Version: Information on what parity bit is to be sent        when mapping is performed through channel coding of data.    -   Layer-1 source ID: ID information on a physical layer of a        sending terminal.    -   Layer-1 destination ID: ID information on a physical layer of a        receiving terminal.    -   Frequency-domain resource assignment for scheduling PSSCH:        Frequency-domain resource configuration information of data        being transmitted.    -   MCS: modulation order and coding rate information.    -   QoS indication: indicates a priority, target latency/delay,        target distance, and target error rate.    -   Antenna port(s): Antenna port information for data transmission.    -   DMRS sequence initialization: information on an ID value for        initialization of a DMRS sequence.    -   PTRS-DMRS association: information on PTRS mapping.    -   CBGTI: utilized as an indicator for code block group (CBG) unit        retransmission.    -   Resource reservation: Information for resource reservation.    -   Time gap between initial transmission and retransmission: Time        interval information between initial transmission and        retransmission.    -   Retransmission index: Indicator for discriminating        retransmission.    -   Transmission format/cast type indicator: Discrimination        indicator of a transmission format or        unicast/groupcast/broadcast.    -   Zone ID: Location information of a transmitting terminal.    -   NACK distance: Reference indicator determining whether a        receiving terminal transmits HARQ-ACK/NACK.    -   HARQ feedback indication: indicates whether a feedback is to be        transmitted or whether the feedback is being transmitted.    -   Time-domain resource assignment for scheduling PSSCH:        Time-domain resource information of sidelink data being        transmitted.    -   Second SCI indication: Indicator including mapping information        of the second SCI for 2-stage control information.    -   DMRS pattern: DMRS pattern (e.g., DMRS-mapped symbol location)        information.

The control information may be included in one SCI to be transmitted tothe receiving terminal, or may be included in two SCIs to betransmitted. The transmission of the control information through twoSCIs may be called a 2-stage SCI method.

The disclosure provides a method in which a terminal having receiveddata in a sidelink transmits a feedback including an HARQ-ACK feedbackand a method and an apparatus in which a terminal having transmitteddata receives a feedback including an HARQ-ACK feedback.

First Embodiment

In a first embodiment, a method and an apparatus are provided, in whicha terminal having received data configures an HARQ-ACK feedback. Amethod is provided for determining the size of an HARQ-ACK codebookregardless of whether actual sidelink data is transmitted and inaccordance with pre-configuration, and a method is provided fordetermining the size of an HARQ-ACK codebook based on whether actualsidelink data is transmitted.

FIG. 16 is a diagram illustrating a mapping structure of physicalchannels mapped onto one slot on a sidelink, according to an embodiment.

A transmitting terminal transmits a preamble signal 1602 on one or moresymbols before transmitting a corresponding slot 1601. The preamblesignal 1602 may be used by a receiving terminal to properly perform anautomatic gain control (AGC) for adjusting the level of amplificationwhen amplifying a power of a received signal. Further, whether totransmit the preamble signal 1602 may be determined depending on whetherthe transmitting terminal has transmitted the previous slot of thecorresponding slot 1601. That is, when the corresponding transmittingterminal transmits a signal to the same terminal as in the previousslot, the preamble transmission may be omitted.

A PSCCH 1603 including control information may be transmitted on initialsymbols of a slot. A PSSCH 1604 being scheduled by the controlinformation of the PSCCH may be transmitted on the initial symbols.Apart of SCI that is the control information may be mapped onto thePSSCH to be transmitted. Further, FIG. 16 illustrates an example inwhich a physical sidelink feedback channel (PSFCH) 1605 that is aphysical channel on which feedback information is transmitted is locatedat the last part of the slot. The terminal enables the terminal havingtransmitted/received the PSSCH to prepare for transmission or receptionof the PSFCH by securing a predetermined empty time between the PSSCH1604 and the PSFCH 1605. After the transmission/reception of the PSFCH1605, the terminal may secure a section emptied for a predeterminedtime.

The terminal may be preconfigured with the location of the slot in whichthe PSFCH can be transmitted. The term “preconfigured” may mean“predetermined” in the terminal preparation process, “transferred” whena sidelink-related system is accessed, “transferred” from the basestation when the base station is accessed, or “transferred” from anotherterminal.

FIG. 17 is a diagram illustrating a resource capable of transmitting andreceiving a PSFCH for each slot, according to an embodiment.

If it is possible to configure a period of resources capable oftransmitting and receiving the PSFCH by a parameter, such asperiodicity_PSFCH_resource, FIG. 17 illustrates a case whereperiodicity_PSFCH_resource=1 slot. Further, it may be possible for theperiod to be configured in units of milliseconds (ms), and a PSFCHresource to be configured in each slot in accordance with the SCS.

FIG. 18 is a diagram illustrating a resource capable of transmitting andreceiving a PSFCH every four slots, according to an embodiment.

As shown in FIG. 18, only a last slot 1804 among four slots 1801, 1802,1803, and 1804 is configured to be able to transmit and receive a PSFCH1811. In a similar manner, only a last slot 1808 among four slots 1805,1806, 1807, and 1808 is configured to be able to transmit and receive aPSFCH 1813. The index of the slot may be a slot that is determined in aresource pool. That is, the four slots 1801, 1802, 1803, and 1804 maynot be physically contiguous slots, but may be contiguously appearingslots among slots belonging to the resource pool (or slot pool) that isused by a transceiver.

Arrows in FIG. 18 indicate slots on the PSFCH on which HARQ-ACK feedbackinformation of the PSSCH is transmitted. The HARQ-ACK information of thePSSCH being transmitted in slots 1801, 1802, and 1803 may be included inthe PSFCH capable of being transmitted in slot 1804. In a similarmanner, the HARQ-ACK information of the PSSCH being transmitted in slots1804, 1805, 1806, and 1807 may be included in the PSFCH capable of beingtransmitted in slot 1808. The reason why the HARQ-ACK feedbackinformation of the PSSCH transmitted in slot 1804 is unable to betransmitted in the same slot 1804 is that there is not enough time forthe terminal to transmit the PSFCH for the PSSCH in the slot 1804 aftercompleting decoding of the PSSCH transmitted in the same slot 1804. Thatis, the minimum processing time required to prepare the PSFCH afterprocessing the PSSCH is not small enough.

In order to properly perform the transmission/reception of the PSFCH, itis necessary to know the number of HARQ-ACK feedback bits included inthe PSFCH. Determination of the number of HARQ-ACK feedback bitsincluded in the PSFCH and of which PSSCH the HARQ-ACK bits are includedmay be performed based on at least one or more combinations of thefollowing parameters.

-   -   Slot period in which the PSFCH can be transmitted and received        by parameters such as periodicity_PSFCH_resource    -   Whether to bundle HARQ-ACK. HARQ-ACK bits of the PSSCH        transmitted in a predetermined number of slots before the PSFCH        transmission and reception may have values determined through an        AND operation (i.e., when bundling is applied, even if one is        NACK, NACK is determined as a whole).    -   The number of transport blocks (TBs) included in PSSCH Whether        to use and configure retransmission in the unit of a code block        group (CBG)    -   Whether to activate HARQ-ACK feedback    -   The number of PSSCHs actually transmitted and received    -   Minimum processing time of a terminal for PSSCH processing and        PSFCH transmission preparation

Slots in which the terminal should transmit the HARQ-ACK may becalculated using the following method. If a PSFCH transmission/receptionresource is configured to be located every N slots, the HARQ-ACK for thePSSCH transmitted in slot n is transmitted in the slot having the indexof ┌(n+1)/N┐×N.

Herein, ┌x┐ means the smallest integer among integers that are largerthan x. The above-described formula may be a formula determined toperform an embodiment of FIG. 18. The above-described formula can beused to be replaced by a formula n+N−mod(n,N).

Herein, mod(a,b) means a remainder obtained by dividing a by b. Forexample, if N is N=4, HARQ-ACK bits of the PSSCH transmitted in slotsn=4, 5, 6, and 7 may be transmitted using the PSFCH in slot 8. Theabove-described equation can be normalized and applied as follows. Ifthe PSFCH transmission/reception resource is located every N slots, theHARQ-ACK for the PSSCH transmitted in slot n is transmitted in a slothaving an index of ┌(n+Δ)/N┐×N.

The above-described formula can be used to be replaced by the formulan+N+Δ−1−mod(n+Δ−1,N).

Here, Δ is a parameter that means a gap between the PSSCH received bythe terminal and the transmission slot of the HARQ-ACK, and may beconfigured for each resource pool, may be a pre-configured value, or maybe understood as the same value between the terminals through thePC5-RRC configuration. As described above, the Δ value may bedifferently defined in accordance with the SCS, and for example, may bea value that is determined or configured as in Table 9 below.

TABLE 9 SCS Δ  15 kHz 1  30 kHz 1  60 kHz 2 120 kHz 2

The proposed Δ value may be variously modified and applied.

The HARQ-ACK timing method may be provided as follows. If the PSFCHtransmission/reception resource is configured to be located every Nslots, the PSFCH being transmitted in slot n includes the HARQ-ACKfeedback information of the PSSCH transmitted in slots n−N, n−N+1, . . ., n−2, n−1.

That is, the PSFCH may include the HARQ-ACK feedback information of thePSSCH transmitted in N slots before the slot n. In FIG. 18, in the PSFCHbeing transmitted in slot n, the HARQ_ACK feedback information for thePSSCH being transmitted in slots n−1, n−2, n−3, and n−4 may be included.The above-described method can be normalized and applied in thefollowing method. That is, it may mean that the PSFCH including theHARQ-ACK feedback for the PSSCH transmitted in slots n−N−Δ+1, n−N−Δ+2, .. . , n−Δ−1, n−Δ is transmitted in slot n.

The above-described method may be applied to secure a time correspondingto about at least Δ slots as the time for the terminal to process thePSSCH and to prepare the PSFCH. If the PSCCH or PSSCH is not received inthe corresponding slot, the receiving terminal may determine theHARQ-ACK value as a fixed value, such as “0”. As described above, the Δis the parameter that means the gap between the PSSCH received by theterminal and the transmission slot of the HARQ-ACK, and may beconfigured for each resource pool, may be a pre-configured value, or maybe understood as the same value between the terminals through thePC5-RRC configuration. Further, the Δ may be differently defined inaccordance with the transmission type, such as the unicast or groupcast.

Second Embodiment

The second embodiment provides a method and an apparatus for determininga HARQ-ACK codebook based on SCI being transmitted from a transmittingterminal.

The transmitting terminal may transmit a PSCCH for scheduling a PSSCH totransmit the PSSCH, and SCI including scheduling information may bemapped onto the PSCCH. The SCI may include the following information.

-   -   Sidelink assignment index (SAI): an indicator indicating which        PSSCH for configuring the HARQ-ACK codebook is transmitted in a        sidelink and indicating how many PSSCHs are configured in one        HARQ-ACK codebook to be transmitted on one PSFCH.

As described above, an SAI bit field may or may not exist in the SCIdepending on the HARQ-ACK codebook configuration information. Further, apart of the SAI bit field may mean the order of PSSCHs in one codebook,such as a counter, in accordance with the configuration information, andthe remaining bits may be used as information indicating the size of thecodebook. Further, the whole SAI bit field information may mean theorder of HARQ-ACK bit values of the corresponding scheduled PSSCHs inaccordance with the configuration information.

Third Embodiment

The third embodiment provides a method and an apparatus for applyingdifferent timing parameters in accordance with the processing capabilityof a terminal when applying the first embodiment.

The terminal may process the SL-SCH included in the PSSCH or data duringreception of the PSSCH, and the processing may include channelestimation, modulation or demodulation, and channel code decoding ofdata. In processing the data, a terminal having a high processingcapability may require a short time required to perform the decoding ofthe data. In contrast, a terminal having a low processing capability mayrequire a long time required to perform the decoding of the data.Accordingly, the timing to transmit the feedback of the data may differdepending on the processing capability of the terminal.

As described above in the first embodiment, if the PSFCHtransmission/reception resource is configured to be located every Nslots, the HARQ-ACK for the PSSCH transmitted in slot n may betransmitted in a slot having an index of ┌(n+Δ)/N┐×N.

The above-described formula can be used to be replaced by the formulan+N+Δ−1−mod(n+Δ−1,N).

Here, is a parameter that means a gap between the PSSCH received by theterminal and the transmission slot of the HARQ-ACK, and may be a valuethat is determined or configured in accordance with the processing timecapability of the terminal, that is, the capability of how fast theterminal can process the PSSCH. In the above-described formula, the Δvalue may be determined as 2 with respect to the terminal capable ofperforming normal processing (in the disclosure, it may be referred toas “capability type 1”), whereas in the above-described formula, the Δvalue may be determined as 1 with respect to the terminal capable ofperforming fast processing (in the disclosure, it may be referred to as“capability type 2”). For example, the Δ value may be provided as inTable 10 below. The information on the processing capability of theterminal may be exchanged between the terminals using the PC5-RRC.

TABLE 10 Δ for Processing Δ for Processing SCS Capability Type 1Capability Type 2  15 kHz 2 1  30 kHz 2 1  60 kHz 3 2 120 kHz 3 2

Embodiment 3-1

Embodiment 3-1 provides a method for determining the number of HARQ-ACKbits or the size of the HARQ-ACK codebook and a time to transmit thefeedback when the terminal intends to transmit the HARQ-ACK on the PSFCHin a state where the PSFCH resource does not exist for each slot and N(N is an integer larger than “1”) is configured.

If the resource capable of transmitting the PSFCH is configured or givenin slot n+x when the terminal receives the PSSCH in slot n, the terminalreceiving the PSSCH maps the HARQ-ACK feedback information of the PSSCHonto the PSFCH in slot n+x to be transmitted using x which is thesmallest one of integers that are equal to or larger than A. Asdescribed above, Δ may be a value preconfigured by the transmittingterminal or may be a value configured in the resource pool from whichthe corresponding PSSCH or PSFCH is transmitted. For the configuration,each terminal may pre-exchange its own capability with the transmittingterminal. As provided in Table 10, Δ may be a value determined inaccordance with at least one of the SCS, the terminal capability,configuration value with the transmitting terminal, or the resource poolconfiguration.

According to the above-described method, when N is N=2, and Δ is “1”,that is, when the PSFCH transmission resource is configured every Nslots in the resource pool, and the HARQ-ACK of the PSSCH can betransmitted in the slot after the minimum Δ=1 from the transmission ofthe PSSCH (i.e., in this case, just next slot), the slot in which theHARQ-ACK feedback is transmitted may be determined as in FIG. 19. FIG.19 is a diagram illustrating the terminal transmitting the HARQ-ACKfeedback, according to an embodiment.

Regarding FIG. 19, the number of HARQ-ACK feedback bits that should betransmitted by the terminal may be 2 bits on all PSFCHs. For example,when the receiving terminal is unable to receive the transmitted PSSCH,or is unable to receive the PSCCH for scheduling the PSSCH both in slotn and in slot n+2, it is not necessary to transmit the PSFCH includingthe HARQ-ACK feedback information in slot n+3. Further, when thereceiving terminal has received the transmitted PSSCH in slot n+3, butis unable to receive the transmitted PSSCH or is unable to receive thetransmitted PSCCH for scheduling the PSSCH in slot n+4, the receivingterminal will be able to transmit one bit of the HARQ-ACK informationfor slot n+3 in slot n+8. Further, when the receiving terminal hasreceived the transmitted PSSCH in slot n+3, but is unable to receive thetransmitted PSSCH or is unable to receive the transmitted PSCCH forscheduling the PSSCH in slot n+4, the receiving terminal will be able totransmit the HARQ-ACK information for slot n+3 and the HARQ-ACKinformation for slot n+4 in slot n+8. In this case, because thereceiving terminal is unable to receive the PSSCH in slot n+4, thereceiving terminal will be able to transmit the feedback throughconfiguration of the HARQ-ACK feedback for slot n+4 to NACK.

That is, when transmitting the PSFCH in a specific slot in considerationof the slot included in the resource pool and the slot in which thePSFCH resource is configured, the period N in which the PSFCH resourceis configured, and the A is configured or determined in accordance withthe processing time of the terminal, the receiving terminal maydetermine the number of HARQ-ACK feedback bits to be included in thePSFCH. The number of HARQ-ACK feedback bits may be determined byEquation (2) below.

The number of HARQ-ACK bits to be included in PSFCH being transmitted inslot n=the number of slots included in a corresponding resource poolamong slot (k−Δ+1) to slot (n−Δ)  (2)

In Equation (2), slot k may be a slot including a PSFCH resourceconfigured to be able to be transmitted just before the PSFCH that canbe transmitted in slot n.

Accordingly, if N and Δ are given, the maximum number of HARQ-ACKfeedback bits to be transmitted by the terminal on one PSFCH may bedetermined as illustrated in FIG. 20. FIG. 20 is a diagram illustratingthe maximum number of HARQ-ACK feedback bits that a terminal shouldtransmit on one PSFCH, according to an embodiment.

That is, in FIG. 20, the terminal may transmit HARQ-ACK feedback bits asmany as the number of corresponding slots on the PSFCH in slot n inconsideration of slot (n−Δ—N+1−Δ+1) to slot (n−Δ). Of course, if theterminal is unable to receive even one transmitted PSSCH or is unable toreceive the transmitted PSCCH for scheduling the PSSCH in slot(n−Δ—N+1−Δ+1) to slot (n−Δ), it may not necessary for the terminal totransmit the PSFCH in slot n. If the N and Δ are given as describedabove, the maximum number of HARQ-ACK feedback bits that should betransmitted by the terminal on one PSFCH may be given as in Equation (3)below.

The maximum number of HARQ-ACK feedback bits that should be transmittedby the terminal on one PSFCH=N+Δ−1  (3)

As an example, when N is N=2, and Δ is “2”, that is, when the PSFCHtransmission resource is configured every N slots in the resource pool,and the terminal can transmit the HARQ-ACK of the PSSCH in the slotafter the minimum Δ=2 from the reception of the PSSCH (i.e., after 2slots, or the slot after next), the slot in which the HARQ-ACK feedbackis transmitted may be determined as in FIG. 21. FIG. 21 is a diagramillustrating the terminal transmitting the HARQ-ACK feedback, accordingto another embodiment.

That is, with reference to FIG. 21, the number of HARQ-ACK feedback bitsthat should be transmitted by the terminal may be 1 bit, 2 bits, or 3bits in accordance with the slot. For example, the terminal will be ableto transmit, in slot n+8, the PSFCH including the HARQ-ACK feedbackinformation as in slot n+2, slot n+3, and slot n+4. When receivingcontrol information for scheduling at least one PSSCH in slot n+2, slotn+3, and slot n+4, the terminal includes 3-bit HARQ-ACK feedbackinformation in the PSFCH to be transmitted, and in the slot in which thePSSCH is unable to be received, the terminal may configure the feedbackinformation to NACK to be transmitted.

Accordingly, when transmitting the feedback through sidelink unicast orgroupcast communication, the number of feedback bits may be determinedas N+Δ−1 as is given in the mathematical expression 3. That is, in thismethod, the example proposed in FIG. 21 is N+Δ−1=2+2−1=3, and thus, itmay be determined to transmit always 3 bits.

As another example, when transmitting the feedback through sidelinkunicast or groupcast communication, the number of feedback bits may bedetermined as the maximum number of bits that should be transmitted inall cases in consideration of the slots belonging to the resource pool,N, and A. That is, in this method, in consideration of FIG. 21, themaximum bit number that can be transmitted in all cases is 3, and thus,it may be determined to transmit always 3 bits.

As another example, when transmitting the feedback through sidelinkunicast or groupcast communication, the number of feedback bits may bedetermined by a method for calculating the number of slots where thePSSCH, which may be related to the HARQ-ACK feedback to be transmittedon the PSFCH in the slot in which the PSFCH is to be transmitted, can betransmitted in consideration of the slots belonging to the resourcepool, N, and Δ. That is, in this method, in consideration of FIG. 21,the terminal may be determined to transmit, on the PSFCH, one bit inslot n, 2 bits in slot n+3, 3 bits in slot n+8, one bit in slot n+12, 2bits in slot n+14, and 2 bits in slot n+16, respectively. Of course, inthe above-described example, if no control signal for scheduling thePSSCH or PSSCH in the slot related to the HARQ-ACK bits to be determinedto be transmitted by the terminal is received, it may be considered thatthe transmitting terminal has not transmitted even one PSSCH, and thus,it may not be necessary for the terminal to transmit the PSFCH includingthe HARQ-ACK.

As another example, when N is N=2, and Δ is “3”, that is, when the PSFCHtransmission resource is configured every N slots in the resource pool,and the HARQ-ACK of the PSSCH can be transmitted in the slot after theminimum Δ=3 from the transmission of the PSSCH (i.e., after 3 slots, orin three slots), the slot in which the HARQ-ACK feedback is transmittedmay be determined as in FIG. 22. FIG. 22 is a diagram illustrating theterminal transmitting the HARQ-ACK feedback, according to anotherembodiment.

That is, with reference to FIG. 22, the number of HARQ-ACK feedback bitsthat should be transmitted by the terminal may be 0 bit, 1 bit, 2 bits,3 bits, or 4 bits in accordance with the slot. For example, the terminalwill be able to transmit, in slot n+8, the PSFCH including the HARQ-ACKfeedback information as in slot n+2, slot n+3, slot n+4, and slot n+5.When receiving control information for scheduling at least one PSSCH inslot n+2, slot n+3, slot n+4, and slot n+5, the terminal includes 4-bitHARQ-ACK feedback information in the PSFCH to be transmitted, and in theslot in which the PSSCH is unable to be received, the terminal mayconfigure the feedback information to NACK to be transmitted.

As another example, when N is N=4, and Δ is “3”, that is, in case thatthe PSFCH transmission resource is configured every 4 slots in theresource pool, and the HARQ-ACK of the PSSCH can be transmitted in theslot after the minimum Δ=3 from the transmission of the PSSCH (i.e., inthis case, after 3 slots, i.e., in three slots), the slot in which theHARQ-ACK feedback is transmitted may be determined as in FIG. 23. FIG.23 is a diagram illustrating the terminal transmitting the HARQ-ACKfeedback, according to another embodiment.

That is, with reference to FIG. 23, the number of HARQ-ACK feedback bitsthat should be transmitted by the terminal may be 2 bits, 3 bits, 4bits, 5 bits, or 6 bits in accordance with the slot. For example, theterminal will be able to transmit, in slot n+12, the PSFCH including theHARQ-ACK feedback information as in slot n+1, slot n+2, slot n+3, slotn+4, slot n+5, and slot n+6. When receiving control information forscheduling at least one PSSCH in slot n+1, slot n+2, slot n+3, slot n+4,slot n+5, and slot 6, the terminal includes 6-bit HARQ-ACK feedbackinformation in the PSFCH to be transmitted, and in the slot in which thePSSCH is unable to be received, the terminal may configure the feedbackinformation to NACK to be transmitted.

As illustrated in FIG. 23, the number of HARQ-ACK feedback bits thatshould be transmitted by the terminal may be increased over N bits inaccordance with N and A. In this case, it is necessary to transmitinformation corresponding to a large number of bits on the PSFCH, andthis may cause a decoding error probability of the PSFCH to beincreased. Accordingly, the terminal may send only the last K bit of thefeedback that should be sent, and may not transmit the remaining bits.As described above, K may be equal to N that is the PSFCH resourceconfiguration period, but is not limited thereto.

As another example, when N is N=2, and Δ is “3”, that is, when the PSFCHtransmission resource is configured every N slots in the resource pool,and the HARQ-ACK of the PSSCH can be transmitted in the slot after theminimum Δ=3 from the transmission of the PSSCH (i.e., after 3 slots, orin three slots), the slot in which the HARQ-ACK feedback is transmittedmay be determined as in FIG. 24. FIG. 24 is a diagram illustrating theterminal transmitting the HARQ-ACK feedback, according to anotherembodiment.

That is, with reference to FIG. 24, the number of HARQ-ACK feedback bitsthat should be transmitted by the terminal may be 0 bit, 1 bit, 2 bits,3 bits, or 4 bits in accordance with the slot. For example, in slotn+12, there may be no sidelink slot in which the corresponding PSSCH, onwhich the HARQ-ACK feedback should be sent, is to be received. That is,a case may exist, in which there is not the feedback bit to betransmitted on the PSFCH resource of a specific slot in accordance withN, Δ, and resource pool configuration, and the minimum number of bits totransmit the HARQ-ACK feedback may be given in Equation (4) below.

The minimum number of HARQ-ACK feedback bits that should be transmittedby the terminal on one PSFCH=max(N−Δ+1,0)  (4)

As described above, max(a, b) is a larger value between a and b. Thatis, in the example provided in FIG. 23, the HARQ-ACK to be transmitteddoes not always exist in slot n+12, and thus, the terminal may considerthat the PSFCH resource does not exist in the corresponding slot. Thatis, although the PSFCH resource exists, the PSSCH transmission/receptionwill be able to be performed through disregarding of the correspondingPSFCH resource.

As an example, N may be configured among values including at least oneof 1, 2, and 4, but is not limited to such an example. Further, theconfiguration may differ for each resource pool.

With respect to HARQ-ACK, the corresponding PSSCH may be a PSSCH forunicast or groupcast, which is configured or indicated to transmit theHARQ-ACK, and is transmitted from the same terminal. That is, on thePSSCH on which it is not necessary to send the HARQ-ACK, it may not benecessary to apply the proposed technique. Further, the PSCCH forscheduling the PSSCH may be control information for scheduling thePSSCH, and it is not always necessary to transmit the controlinformation on the PSCCH. Further, although the control information maybe one piece of control information, a plurality of pieces of controlinformation may schedule one PSSCH.

The above-described contents may be modified and applied as follows.When receiving the PSSCH in slot n, the terminal having received thePSSCH transmits HARQ-ACK feedback information of the PSSCH on the PSFCHthat is fastest among PSFCHs having a gap between the PSSCH and thePSFCH that is equal to or larger than y symbols. Here, y may be a valuepreconfigured by the transmitting terminal or a value configured in theresource pool from which the corresponding PSSCH or PSFCH istransmitted. For the above-described configuration, each terminal maypre-exchange its own capability with the transmitting terminal, or y maybe determined in accordance with the subcarrier spacing.

Embodiment 3-2

Embodiment 3-2 provides a method and an apparatus for configuring aPSFCH resource in a resource pool.

In accordance with the resource pool configuration, physicallycontiguous or non-contiguous slots may belong to one resource pool. Withrespect to the slots belonging to the resource pool, logical slotnumbers (indexes) may be contiguously given. The slots belonging to aspecific resource pool may have logically contiguous slot indexes, butmay not be physically contiguous slots. FIG. 25 is a diagramillustrating physical slot indexes and logical slot indexes of slotsincluded in a resource pool configured in accordance with resource poolconfiguration in physical slots, according to an embodiment.

As illustrated in FIG. 25, when physical slots n+4, n+5, and n+6 are notincluded in the resource pool, slot n+7 may be included in the resourcepool after slot n+3, and logical slot indexes may be contiguously givento slot k+3 and slot k+4.

As in the method provided in the previous embodiments, the PSFCHresource may be periodically configured every N slots in the resourcepool (i.e., the PSFCH resource is periodically configured every N slotsusing the logical slot indexes), and in contrast, the PSFCH resource maybe periodically configured every N slots using physical slot indexes.According to this method, the PSFCH resource may not be periodicallyconfigured in the logical slot indexes.

The number of HARQ-ACK feedback bits that should be transmitted by theterminal may be increased over N bits in accordance with N and A. Inthis case, it is necessary to transmit information corresponding to alarge number of bits on the PSFCH, and this may cause a decoding errorprobability of the PSFCH to be increased. Accordingly, the terminal maysend only the last K bit of the feedback that should be sent, and maynot transmit the remaining bits. As described above, K may be equal to Nthat is the PSFCH resource configuration period, but is not limitedthereto.

Fourth Embodiment

The fourth embodiment provides a method and an apparatus capable ofsolving or mitigating the problem that one terminal should perform bothtransmission and reception of the PSFCH in a state where the PSFCHresource does not exist for each slot and N (N is an integer that islarger than “1”) is configured. This problem may occur due tohalf-duplex restriction in that the terminal is unable to simultaneouslyperform transmission and reception of signals.

FIG. 26 is a diagram illustrating terminal 1 (UE1) and terminal 2 (UE2)transmitting PSFCHs in the same slot for HARQ-ACK feedback transmissionfor respective transmitted PSSCHs when the terminal 1 and the terminal 2perform signal transmission and reception by a connection throughunicast or groupcast communication in a sidelink, according to anembodiment.

Terminal 1 has transmitted a PSSCH 2602 to terminal 2 in slot 1 2600,and terminal 2 has transmitted a PSSCH 2612 to terminal 1 in slot 22610. In accordance with the feedback transmission timing, the feedbacktiming may be determined so that terminal 2 transmits, in slot 4 2620,the HARQ-ACK feedback for the PSSCH transmitted from terminal 1 toterminal 2 in slot 1, and terminal 1 transmits, in slot 4 2620, theHARQ-ACK feedback for the PSSCH transmitted from terminal 2 to terminal1 in slot 2. Terminal 2 may transmit the PSFCH including the feedbackinformation for the PSSCH transmitted in slot 1 to terminal 1, andterminal 1 may transmit the PSFCH including the feedback information forthe PSSCH transmitted in slot 2 to terminal 2. Terminal 1 and terminal 2should perform both the transmission and reception of a PSFCH 2622, andthe transmission and reception of the PSFCH 2622 may be performed in thesame symbol.

If a terminal is unable to simultaneously perform transmission andreception of certain signals, the above-described support may not beperformed. The terminal being unable to simultaneously performtransmission and reception of a certain signal may be a case in whichthe terminal has a half-duplex restriction, and in contrast, theterminal being able to simultaneously perform transmission and receptionof a certain signal may be a case in which the terminal has afull-duplex function.

When the terminal that is considered as a half-duplex terminal isconfigured to perform transmission or reception of the PSFCH withoutsimultaneously performing transmission and reception, as the terminalselects and performs the transmission or reception of the sidelink, itmay be possible to combine and apply one or more of the followingmethods.

-   -   Method 1: Whether to perform transmission/reception of the PSFCH        may be determined based on SCI for scheduling the PSSCH. In this        method, it is possible to determine what terminal receives the        PSFCH and what terminal transmits the PSFCH based on a bit field        value included in the SCI transmitted or received by the        terminal. For example, terminal 1 may compare a QoS value (a        value of priority, latency, delay, PQI, or 5QI) that is included        in the SCI included in the PSCCH when terminal 1 transmits the        PSSCH 2602 in slot 1 with a QoS value included in the PSCCH for        scheduling the PSSCH 2612 received from terminal 2 in slot 2,        and may determine to transmit and receive the HARQ-ACK feedback        of the PSSCH corresponding to higher QoS (or having a value        corresponding to a higher priority).

If the priority value that is included in the SCI included in the PSCCH2612 transmitted together when terminal 1 transmits the PSSCH in slot 1is “1”, and the priority value included in the PSCCH for scheduling thePSSCH 2612 received from terminal 2 in slot is “4” (it is assumed thatpriority 1 is higher than priority 4), terminal 1 receives the PSFCH inthe slot 4 2620, terminal 2 transmits the PSFCH in the slot 4 2620, andthe PSFCH may include the HARQ-ACK feedback information for the PSSCHtransmitted by terminal 1 in the slot 1 2600. If the QoS valuescorresponding to the PSSCHs transmitted by the terminals are equal toeach other, whether to transmit the PSFCH may be determined so that thePSFCH including the HARQ-ACK information for the earlier transmittedPSSCH is transmitted based on the earlier transmitted PSSCH.

-   -   Method 2: Whether to perform transmission/reception of the PSFCC        may be determined in accordance with the order of PSSCH        transmission. In this method, it may be determined what terminal        receives the PSFCH and what terminal transmits the PSFCH based        on the transmission/reception slot index order of the PSSCH        transmitted or received by the terminal, that is, based on what        PSSCH is first transmitted. This method may be determined by the        timing in which the PSFCH including the HARQ-ACK for the        transmitted PSSCH is transmitted.

If the PSFCH transmission/reception resource is located every N slots,the HARQ-ACK for the PSSCH transmitted in slot n is transmitted in slot┌(n+Δ)/N┐×N. Further, the HARQ-ACK may be transmitted in slotn+N+Δ−1−mod(n+Δ−1,N). Here, Δ is a parameter defining a gap between thePSSCH received by the terminal and the transmission slot of theHARQ-ACK, and may be configured for each resource pool, may be apre-configured value, or may be understood to the terminals through thePC5-RRC configuration. As described above, the Δ value may bedifferently defined in accordance with the SCS. That is, it means thatthe PSFCH including the HARQ-ACK feedback for the PSSCH transmitted inslot n−N−Δ+1, n−N−Δ+2, . . . , n−Δ−1, n−Δ is transmitted in slot n.

If terminal 1 has transmitted the PSCCH to terminal 2 in slot n−N−Δ+1,and terminal 2 has transmitted the PSSCH to terminal 1 in slot n−N−Δ+2,all the HARQ-ACK feedback information for the two PSSCHs should betransmitted in slot n. According to this method, the first transmittedPSSCH, that is, the PSFCH including the HARQ-ACK for the PSSCH thatterminal 1 has transmitted to terminal 2 in slot n−N−Δ+1, may betransmitted/received in slot n. As described above, terminal 1 mayreceive the PSFCH in slot n, terminal 2 may transmit the PSFCH in slotn, and the PSFCH may include the HARQ-ACK for the PSSCH that theterminal 1 has transmitted to terminal 2 in slot.

Fifth Embodiment

The fifth embodiment provides a method and an apparatus capable ofsolving or mitigating the problem that one terminal should transmit thePSFCH to several terminals in a state where the PSFCH resource does notexist for each slot and N (N is an integer that is larger than “1”) isconfigured. This problem may occur due to a restriction in that theterminal is able to transmit only one physical channel at a time. APSFCH transmission method has been described when one terminal shouldtransmit the PSFCH to several terminals, but it will be also possible toapply the contents of this embodiment even when one terminal transmits aplurality of PSFCHs according to a plurality of transmission types toone or two or more terminals. That is, this embodiment can also beapplied when one terminal should transmit the PSFCH for unicast and thePSFCH for groupcast to other terminals in the same symbol in the sameslot.

FIG. 27 is a diagram illustrating a time when terminal 1 (UE1) shouldtransmit two PSFCHs in the same slot for HARQ-ACK feedback transmissionfor PSSCHs that terminal 2 (UE2) and terminal 3 (UE3) have transmittedto terminal 1 (UE1) when UE1 performs signal transmission and receptionwith UE2 and UE3 by a connection through unicast or groupcastcommunication, according to an embodiment. As described above, terminal2 and terminal 3 may be different from each other, or may be the sameterminal. The PSFCH transmission method has been described when oneterminal should transmit the PSFCH to several terminals, but if thisembodiment is applied when one terminal transmits a plurality of PSFCHsaccording to a plurality of transmission types to one terminal, theterminal 2 and terminal 3 may be the same terminal.

UE2 has transmitted PSSCH 2702 to UE1 in slot 1 2700, and UE3 hastransmitted PSSCH 2712 to UE1 in slot 2 2710. The PSFCHtransmission/reception timing may be determined so that UE1 transmitsHARQ-ACK feedback information for two PSSCHs to UE2 and UE3 in slot 42720 by encoding the HARQ-ACK feedback information on PSFCHs 2722. IfUE1 can transmit the PSFCH (hereinafter, PSFCH 2) to UE2 and the PSFCH(hereinafter, PSFCH 3) to UE3 in all in the slot 4 2720, UE2 and UE3 cansimultaneously receive the PSFCH from UE1, and can identify the HARQ-ACKfeedback information for the PSSCH sent by UE2 and UE3 themselves.However, if the UE1 is unable to simultaneously transmit PSFCH 2 andPSFCH 3 in the slot 4 2720, it is necessary for UE1 to determine whichPSFCH UE1 should transmit. The reason why UE1 is unable tosimultaneously transmit PSFCH 2 and PSFCH 3 may be that insufficienttransmission power is provided, and if divided power is used for each ofthe PSFCHs, the coverage of the respective PSFCHs may be reduced.

It may be possible to combine and apply one or more of the following asmethods in which the terminal selects and transmits (or receives) onePSFCH to prevent the terminal from simultaneously transmitting orreceiving two or more PSFCHs.

-   -   Method 1: The PSFCH that the terminal is to transmit/receive may        be determined based on SCI for scheduling the PSSCH. In this        method, it is possible to determine the PSSCH to which the PSFCH        corresponds that the terminal is to transmit based on bit field        values included in the received SCI. For example, as illustrated        in FIG. 27, terminal 1 may compare a QoS value (a value of        priority, latency, delay, PQI, or 5QI) that is included in the        SCI included in the PSCCH transmitted together for the        corresponding PSSCH scheduling when terminal 2 transmits the        PSSCH 2702 to terminal 1 in the slot 1 2700 with a QoS value        included in the SCI included in the PSCCH transmitted together        for the corresponding PSSCH scheduling when terminal 3 transmits        the PSSCH 2712 to terminal 1 in the slot 2 2710, and the        terminal 1 may determine to transmit and receive the HARQ-ACK        feedback of the PSSCH corresponding to higher QoS (or having a        value corresponding to a higher priority).

For example, if the priority value that is included in the SCI includedin the PSCCH transmitted for scheduling of the PSSCH 2702 received fromterminal 2 in the slot 1 2700 is “1”, and the priority value included inthe SCI included in the PSCCH transmitted for scheduling of the PSSCH2712 received from terminal 3 in the slot 2 2710 is “4” (it is assumedthat priority 1 is higher than priority 4), terminal 1 transmits thePSFCH to terminal 2 in the slot 4 2720, and the PSFCH may include theHARQ-ACK feedback information for the PSSCH transmitted by terminal 2 inthe slot 1 2700. If the QoS values corresponding to the PSSCHstransmitted by the terminals are equal to each other, whether totransmit the PSFCH may be determined so that the PSFCH including theHARQ-ACK information for the earlier transmitted PSSCH is transmittedbased on the earlier transmitted PSSCH.

-   -   Method 2: The PSFCH that the terminal is to transmit may be        determined in accordance with the order of PSSCH transmission.        In this method, it may be determined whether to transmit the        PSFCH including the HARQ-ACK for what PSSCH based on the        transmission/reception slot index order of the PSSCH transmitted        or received by the terminal, that is, based on what PSSCH is        first transmitted. This method may be determined by the timing        in which the PSFCH including the HARQ-ACK for the transmitted        PSSCH is transmitted.

For example, if the PSFCH transmission/reception resource is locatedevery N slots, the HARQ-ACK for the PSSCH transmitted in slot n istransmitted in slot ┌(n+Δ)/N┐×N. Further, the HARQ-ACK may betransmitted in slot n+N+Δ−1−mod(n+Δ−1,N). Here, Δ is a parameterdefining a gap between the PSSCH received by the terminal and thetransmission slot of the HARQ-ACK, and may be configured for eachresource pool, may be a pre-configured value, or may be understood tothe terminals through the PC5-RRC configuration. As described above, theΔ value may be differently defined in accordance with the SCS. That is,the PSFCH including the HARQ-ACK feedback for the PSSCH transmitted inslot n−N−Δ+1, n−N−Δ+2, . . . , n−Δ−1, n−Δ is transmitted in slot n.

If terminal 1 has received the PSCCH from terminal 2 in slot n−N−Δ+1,and terminal 1 has also received the PSSCH from terminal 3 in slotn−N−Δ+2, all the HARQ-ACK feedback information for the two PSSCHs shouldbe transmitted in slot n. According to this method, the firsttransmitted PSSCH, that is, the PSFCH including the HARQ-ACK for thePSSCH that terminal 1 has received from terminal 2 in slot n−N−Δ+1, maybe transmitted/received in slot n. As described above, both terminal 2and terminal 3 attempt to perform decoding of the PSFCH in slot n, andbecause terminal 1 has transmitted the PSFCH to terminal 2, onlyterminal 2 may be successful in receiving the PSFCH.

-   -   Method 3: The terminal can simultaneously transmit feedback        information to two or more terminals using one PSFCH. This        method may be determined by the timing in which the PSFCH        including the HARQ-ACK for the transmitted PSSCH is transmitted.        If the PSFCH transmission/reception resource is located every N        slots, the HARQ-ACK for the PSSCH transmitted in slot n is        transmitted in slot ┌(n+Δ)/N┐×N. Further, the HARQ-ACK may be        transmitted in slot n+N+Δ−1−mod(n+Δ−1,N). Here, Δ is a parameter        defining a gap between the PSSCH received by the terminal and        the transmission slot of the HARQ-ACK, and may be configured for        each resource pool, may be a pre-configured value, or may be        understood to the terminals through the PC5-RRC configuration.        As described above, the Δ value may be differently defined in        accordance with the SCS. That is, it may mean that the PSFCH        including the HARQ-ACK feedback for the PSSCH transmitted in        slot n−N−Δ+1, n−N−Δ+2, . . . , n−Δ−1, n−Δ is transmitted in        slot n. If terminal 1 has received the PSCCH from terminal 2 in        slot n−N−Δ+1, and terminal 1 has also received the PSSCH from        terminal 3 in slot n−N−Δ+2, all the HARQ-ACK feedback        information for the two PSSCHs should be transmitted in slot n.

According to this method, when transmitting N pieces of HARQ-ACKinformation in slot n, terminal 1 may deploy the HARQ-ACK informationfor the PSSCH received from terminal 2 in slot n−N−Δ+1 at the firstlocation of the N pieces of HARQ-ACK information, and may deploy theHARQ-ACK information for the PSSCH received from terminal 3 in slotn−N−Δ+2 at the second location of the N pieces of HARQ-ACK informationto be transmitted. If terminal 1 is unable to receive the PSSCH in acertain slot in a predetermined section, the terminal may configure theHARQ-ACK feedback codebook by configuring the HARQ-ACK feedbackcorresponding to the slot to a predetermined value. For example,terminal 1 may determine the HARQ-ACK feedback value for the PSSCH thathas not been trasnmitted as a value that means NACK.

-   -   Method 4: Whether to transmit the PSFCH may be determined in        accordance with the number of feedback bits that should be        transmitted by the terminal. If it is required for terminal 1 to        transmit the feedback to terminal 2 and terminal 3, the feedback        is transmitted to the terminal that requires a larger amount of        feedback on the PSFCH. If the same amount of feedback is to be        transmitted to terminal 2 and terminal 3, the terminal may        optionally determine to what terminal the feedback is to be        transmitted, or parts or combination of the above-described        methods 1, 2, and 3 may be applied.    -   Method 5: The terminal may transmit a plurality of PSFCHs        including the feedback to be transmitted. However, when        transmitting a plurality of PSFCHs, if the sum of powers being        used for the PSFCH transmission is larger than the maximum power        the terminal P_(c,max) that can be used by the terminal for the        sidelink transmission, the terminal reduces the power of the        ASFCH in the original PSFCH power ratio so that the sum of all        the PSFCH powers becomes P_(c,max), and transmits the reduced        power. For example, when the terminal should transmit PSFCH1 and        PSFCH2, respective calculated powers are P1 and P2, and        P1+P2>P_(c,max), the terminal may determine the power of PSFCH1        as P_(c,max)cP1/(P1+P2), and may determine the power of PSFCH2        as P_(c,max)xP2/(P1+P2). The sum of the powers of PSFCH1 and        PSFCH2 becomes P_(c,max).    -   Method 6: Whether to transmit the PSFCH may be determined in        accordance with the number of pieces of scheduling control        information received by the terminal. That is, whether to        transmit the PSFCH is determined in accordance with the number        of PSSCHs scheduled to be received by the terminal. If it is        required for terminal 1 to transmit the feedback to terminal 2        and terminal 3, the feedback is transmitted to the terminal that        is scheduled to receive a larger number of PSSCHs on the PSFCH.        If the same number of PSSCHs are scheduled from terminal 2 and        terminal 3, the terminal may optionally determine to what        terminal the feedback is to be transmitted, or parts or        combination of the above-described methods 1, 2, 3, 4, and 5 may        be applied.

As described above, for convenience in explanation, the first to fifthembodiments have been described individually. However, the respectiveembodiments include related operations, and thus, it is possible tocombine at least two embodiments.

In order to perform the above-described embodiments of the disclosure,transmitters, receivers, and processors of a terminal and a base stationare illustrated in FIGS. 28 and 29. In the first and second embodiments,in order to perform operations of configuring the HARQ-ACK feedbackinformation, determining whether to transmit the HARQ-ACK feedback, andtransmitting the feedback, the transmission/reception method between thebase station and the terminal or between the transmitting end and thereceiving end has been provided, and in order to perform the method, thereceivers, processors, and transmitters of the base station and theterminal should operate according to the respective embodiments.

Specifically, FIG. 28 is a block diagram illustrating the internalstructure of a terminal, according to an embodiment. As illustrated inFIG. 28, the terminal includes a terminal receiver 2800, a terminaltransmitter 2804, and a terminal processor 2802. The terminal receiver2800 and the terminal transmitter 2804 may be commonly called atransceiver. The transceiver may transmit/receive a signal with a basestation. The signal may include control information and data. For this,the transceiver may be composed of an RF transmitter for up-convertingand amplifying the frequency of a transmitted signal, and an RF receiverfor low-noise-amplifying and down-converting the frequency of a receivedsignal. Further, the transceiver may receive a signal through a radiochannel, and may output the received signal to the terminal processor2802. The transceiver may also transmit the signal that is output fromthe terminal processor 2802 on the radio channel. The terminal processor2802 may control a series of processes so that the terminal operatesaccording to the above-described embodiments of the disclosure. Forexample, the terminal receiver 2800 receives control information fromthe base station, the terminal processor 2802 determines whether totransmit the HARQ-ACK feedback and feedback information in accordancewith the control information and preconfigured configurationinformation. Thereafter, the terminal transmitter 2804 may transfer thescheduled feedback to the base station.

FIG. 29 is a diagram illustrating the internal structure of a basestation, according to an embodiment. As illustrated in FIG. 29, a basestation includes a base station receiver 2901, a base stationtransmitter 2905, and a base station processor 2903. The base stationreceiver 2901 and the base station transmitter 2905 may be commonlycalled a transceiver. The transceiver may transmit/receive a signal witha terminal. The signal may include control information and data. Forthis, the transceiver may be composed of an RF transmitter forup-converting and amplifying the frequency of a transmitted signal, andan RF receiver for low-noise-amplifying and down-converting thefrequency of a received signal. Further, the transceiver may receive asignal through a radio channel, and may output the received signal tothe base station processor 2903. The transceiver may also transmit thesignal that is output from the base station processor 2903 through theradio channel. The base station processor 2903 may control a series ofprocesses so that the base station operates according to theabove-described embodiments of the disclosure. For example, the basestation processor 2903 may control to configure control information inaccordance with HARQ-ACK feedback information of the terminal and toreceive the feedback in accordance with the control information.Thereafter, the base station transmitter 2905 transmits relatedscheduling control information, and the base station receiver 2901receives the feedback information together with the schedulinginformation.

Embodiments of the disclosure described herein are merely for easyexplanation of the technical contents of the disclosure and proposal ofspecific examples to help understanding of the disclosure, but are notintended to limit the scope of the disclosure. That is, it will beapparent to those of ordinary skill in the art to which the disclosurepertains that other modified examples that are based on the technicalidea of the disclosure can be embodied. Further, according tocircumstances, the respective embodiments may be operated incombination. Further, other modified examples based on the technicalidea of the above-described embodiments may be embodied in an LTE systemand 5G system.

While the disclosure has been shown and described with reference tocertain embodiments thereof, it will be understood by those skilled inthe art that various changes in form and detail may be made thereinwithout departing from the spirit and scope of the disclosure as definedby the appended claims.

What is claimed is:
 1. A method performed by a terminal in acommunication system, the method comprising: receiving, from one or moreterminals, a plurality of sidelink data including first sidelink dataand second sidelink data; determining whether a first resource fortransmitting first feedback information for the first sidelink data anda second resource for transmitting second feedback information for thesecond sidelink data overlap each other; and in case that the firstresource and the second resource overlap each other, transmitting, toone or more terminals, feedback information corresponding to one of thefirst feedback information and the second feedback information having ahigher priority, wherein a priority corresponding to each of theplurality of the sidelink data is based on sidelink control informationscheduling each of the plurality of the sidelink data.
 2. The method ofclaim 1, wherein the priority is indicated by a field of the sidelinkcontrol information.
 3. The method of claim 1, further comprising:transmitting, to another terminal, third sidelink data; receiving, fromanother terminal, fourth sidelink data; identifying whether a thirdresource for receiving third feedback information for the third sidelinkdata and a fourth resource for transmitting fourth feedback informationoverlap each other; and in case that the third resource and the fourthresource overlap each other, transmitting or receiving feedbackinformation corresponding to one of the third feedback information andthe fourth feedback information having a higher priority.
 4. The methodof claim 1, wherein resources for feedback information are identifiedbased on a period of the resources and a minimum number of slots betweensidelink data and corresponding feedback information.
 5. The method ofclaim 4, wherein the period of the resources and the minimum number ofslots are included in resource pool configuration information.
 6. Themethod of claim 4, wherein the feedback information is transmitted in afirst slot among a plurality of slots including the resources.
 7. Aterminal in a communication system, the terminal comprising: atransceiver; and a controller configured to: receive, from one or moreterminals via the transceiver, a plurality of sidelink data includingfirst sidelink data and second sidelink data, determine whether a firstresource for transmitting first feedback information for the firstsidelink data and a second resource for transmitting second feedbackinformation for the second sidelink data overlap each other, and in casethat the first resource and the second resource overlap each other,transmit, to one or more terminals via the transceiver, feedbackinformation corresponding to one of the first feedback information andthe second feedback information having a higher priority, wherein apriority corresponding to each of the plurality of the sidelink data isbased on sidelink control information scheduling each of the pluralityof the sidelink data.
 8. The terminal of claim 7, wherein the priorityis indicated by a field of the sidelink control information.
 9. Theterminal of claim 7, wherein the controller is further configured to:transmit, to another terminal via the transceiver, third sidelink data,receive, from another terminal via the transceiver, fourth sidelinkdata, identifying whether a third resource for receiving third feedbackinformation for the third sidelink data and a fourth resource fortransmitting fourth feedback information overlap each other, and in casethat the third resource and the fourth resource overlap each other,transmit or receive, via the transceiver, feedback informationcorresponding to one of the third feedback information and the fourthfeedback information having a higher priority.
 10. The terminal of claim7, wherein resources for feedback information are identified based on aperiod of the resources and a minimum number of slots between sidelinkdata and corresponding feedback information.
 11. The terminal of claim10, wherein the period of the resources and the minimum number of slotsare included in resource pool configuration information.
 12. Theterminal of claim 10, wherein the feedback information is transmitted ina first slot among a plurality of slots including the resources.